
AVIATION 

ENGINES 
















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■ 







VC|\^ 



3^ 



JUST PUBLISHED 

AVIATION ENGINES. Their Design, Construction, 
Operation and Repair. 

By Lieut. Victor W. Page, Aviation Section, S.C.U.S.R. 

A practical work containing valuable instructions for aviation 
students, mechanicians, squadron engineering officers and all inter- 
ested in the construction and upkeep of airplane power plants. 
576 octavo pages. 250 illustrations. Price $3.00. 

AVIATION CHART, or the Location of Airplane Power 
Plant Troubles Made Easy. 

By Lieut. Victor W. Page, A.S., S.C.U.S.R. 

A large chart outlining all parts of i typical airplane power plant, 
showing the points where trouble is apt to occur and suggesting 
remedies for the common defects. Intended especially for aviators 
and aviation mechanics on school and field duty. Price 50 cents. 

GLOSSARY OF AVIATION TERMS. 

Compiled by Lieuts. Victor W. Page, A.S., S.C.U.S.R. and 

Paul Moxtariol of the French Flying Corps on duty at 

Signal Corps Aviation School, Mineola, L. I. 

A complete glossary of practically all terms used in aviation, 

having lists in both French and English, with equivalents in either 

language. A very valuable book for all who are about to leave 

for duty overseas. Price, cloth, §1.00. 



THE 



NORMAN W. HENLEY PUBLISHING COMPANY 

2 WEST 45th ST., NEW YORK 



CENSORED 

This Book Entitled 

AVIATION ENGINES 

By LIEUT. VICTOR W. PAGE 

has been censored by the United States Govern- 
ment, and pages and parts of pages have been 
omitted by special instructions from Washington. 

The book has been passed by THE COM- 
MITTEE ON PUBLIC INFORMATION and 

is as complete as we can furnish it, and we so 
advise the purchaser of it. 

THE NORMAN W. HENLEY PUBLISHING COMPANY 



Fulcrum 



Cam Shaft— - 
Oil Jacket- 



Safety Gas-'' 
Wrist Pin--''' 
Connecting Rod" 

Crankshaft'"' 

Crank Pin — -" 
Bearing Box-'' 



^.-Regulating Screw 

1 s'Key^,, Valve Spring Collar 

ValveSpring 
—-Valve Stem 

Valve Stem Guide 
'"^-Exhaust Pipe 

. - Spark Plug 
^"-5 park Plug Wire 
'—-Pet Cock 
\\"~- Valve Seat 
W'VY/'re Conduit 
] M K Water Jacket 




Sump-''' 



Drain Plug or Nut 



Drain Cock' 



A.6.HAGSTR0M N.Y 



Part Sectional View of Hall-Scott Airplane Motor, Showing 
Principal Parts. 



AVIATION ENGINES 

Design — Construction — Operation and Repair 



A COMPLETE, PRACTICAL TREATISE OUTLINING CLEARLY 
THE ELEMENTS OF INTERNAL COMBUSTION ENGINEERING 
WITH SPECIAL REFERENCE TO THE DESIGN, CONSTRUC- 
TION, OPERATION AND REPAIR OF AIRPLANE POWER 
PLANTS; ALSO THE AUXILIARY ENGINE SYSTEMS, SUCH 
AS LUBRICATION, CARBURETION, IGNITION AND COOLING. 

IT INCLUDES COMPLETE INSTRUCTIONS FOR ENGINE 

REPAIRING AND SYSTEMATIC LOCATION OF TROUBLES, 

TOOL EQUIPMENT AND USE OF TOOLS, ALSO OUTLINES 

THE LATEST MECHANICAL PROCESSES. 



BY.^ 

FIRST LIEUT. VICTOR W. PAGE, A. S. S. C, U. S. R. 

Assistant Engineering Officer, Signal Corps Aviation School, Mineola, L. I. 
Author of " The Modern Gasoline Automobile," Etc. 




CONTAINS VALUABLE INSTRUCTIONS FOR ALL AVIATION STUDENTS, MECH- 
ANICIANS, SQUADRON ENGINEERING OFFICERS AND ALL INTERESTED IN 
THE CONSTRUCTION AND UPKEEP OF AIRPLANE POWER PLANTS. 



NEW YORK 

THE NORMAN W. HENLEY PUBLISHING CO. 

2 WEST 45th STREET 
1919 






Copyrighted, 1917 

BY 

The Norman W. Henley Publishing Co. 



PRINTED IN U. S. A. 



THIRD IMPRESSION 



ALL ILLUSTRATIONS IN THIS BOOK HAVE BEEN 
SPECIALLY MADE BY THE PUBLISHERS, AND THEIR 
USE, WITHOUT PERMISSION, IS STRICTLY PROHIBITED 



By .ExJiAn«$ 
Mlddlfttown De#otSU$£w 



press or 

BRAUNWORTH & CO. 

BOOK MANUFACTURER9 

BROOKLYN. N. Yo 



31- 13^3 7 



PREFACE 

In presenting this treatise on "Aviation Engines,' ' 
the writer realizes that the rapidly developing art makes 
it difficult to outline all latest forms or describe all 
current engineering practice. This exposition has been 
prepared primarily for instruction purposes and is adapted 
for men in the Aviation Section, Signal Corps, and 
students who wish to become aviators or aviation mech- 
anicians. Every effort has been made to have the engi- 
neering information accurate, but owing to the diversity 
of authorities consulted and use of data translated from 
foreign language periodicals, it is expected that some 
slight errors will be present. The writer wishes to ac- 
knowledge his indebtedness to such firms as the Curtiss 
Aeroplane and Motor Co., Hall-Scott Company, Thomas- 
Morse Aircraft Corporation and General Vehicle Com- 
pany for photographs and helpful descriptive matter. 
Special attention has been paid to instructions on tool 
equipment, use of tools, trouble "shooting" and engine 
repairs, as it is on these points that the average aviation 
student is weakest. Only such theoretical consideration 
of thermo-dynamics as was deemed absolutely necessary 
to. secure a proper understanding of engine action after 
consulting several instructors is, included, the writer's 
efforts having been confined to the preparation of a 
practical series of instructions that would be of the 
greatest value to those who need a diversified knowledge 
of internal-combustion engine operation and repair, and 

9 



10 Preface 

who must acquire it quickly. The engines described and 
illustrated are all practical forms that have been fitted to 
airplanes capable of making flights and may be considered 
fairly representative of the present state of the art. 

Victok W. Page, 
1st Lieut. A. S. S. C, U. 8. R. 

MlNEOLA, L. I., 
January, 1919. 



CONTENTS 

CHAPTER I 

PAGES 

Brief Consideration of Aircraft Types — Essential Requirements of Aerial 
Motors — Aviation Engines Must Be Light — Factors Influencing 
Power Needed — Why Explosive Motors Are Best — Historical — Main 
Types of Internal Combustion Engines 17-36 



CHAPTER II 

Operating Principles of Two- and Four-Stroke Engines — Four-cycle 
Action — Two-cycle Action — Comparing Two- and Four-cycle Types 
— Theory of Gas and Gasoline Engine — Early Gas-Engine Forms — 
Isothermal Law — Adiabatic Law — Temperature Computations — 
Heat and Its "Work — Conversion of Heat to Power — Requisites for 
Best Power Effect 37-59 



CHAPTER III 

Efficiency of Internal Combustion Engines — Various Measures of Effi- 
ciency — Temperatures and Pressures — Factors Governing Economy 
— Losses in Wall Cooling — Value of Indicator Cards — Compression 
in Explosive Motors — Factors Limiting Compression — Causes of 
Heat Losses and Inefficiency — Heat Losses to Cooling Water . 60-79 



CHAPTER IV 

Engine Parts and Functions — Why Multiple Cylinder Engines Are Best 
— Describing Sequence of Operations — Simple Engines — Four and 
Six Cylinder Vertical Tandem Engines — Eight and Twelve Cylinder 
V Engines — Radial Cylinder Arrangement — Rotary Cylinder 
Forms 80-109 



CHAPTER V 

Properties of Liquid Fuels — Distillates of Crude Petroleum — Principles 
of Carburetion Outlined — Air Needed to Burn Gasoline — What a 
Carburetor Should Do — Liquid Fuel Storage and Supply — Vacuum 
Fuel Feed — Early Vaporizer Forms — Development of Float 

11 



12 Contents 



PAGES 

Feed Carburetor — Maybach's Early Design — Concentric Float and 
Jet Type — Schebler Carburetor — Claudel Carburetor — Stewart 
Metering Pin Type — Multiple Nozzle Vaporizers — Two-Stage Car- 
buretor — Master Multiple Jet Type — Compound Nozzle Zenith Car- 
buretor — Utility of Gasoline Strainers — Intake Manifold Design and 
Construction — Compensating for Various Atmospheric Conditions — 
How High Altitude Affects Power — The Diesel System — Notes on 
Carburetor Installation — Notes on Carburetor Adjustment . 110-154 



CHAPTER VI 

Early Ignition Systems — Electrical Ignition Best — Fundamentals of 
Magnetism Outlined — Forms of Magneto — Zones of Magnetic In- 
fluence — How Magnets are Made — Electricity and Magnetism Re- 
lated — Basic Principles of Magneto Action — Essential Parts of 
Magneto and Functions — Transformer Coil Systems — True High 
Tension Type — The Berling Magneto — Timing and Care — The Dixie 
Magneto — Spark-Plug Design and Application — Two-Spark Ignition 
Special Airplane Plug .- 155-200 



CHAPTER VII 

"Why Lubrication Is Necessary — Friction Defined — Theory of Lubrica- 
tion — Derivation of Lubricants — Properties of Cylinder Oils — Fac- 
tors Influencing Lubrication System Selection — Gnome Type Engines 
Use Castor Oil — Hall-Scott Lubrication System — Oil Supply by 
Constant Level Splash System — Dry Crank-Case System Best for 
Airplane Engines — Why Cooling Systems Are Necessary — Cooling 
Systems Generally Applied — Cooling by Positive Pump Circulation 
— Thermo-Syphon System — Direct Air-Cooling Methods — Air- 
Cooled Engine Design Considerations 201-232 



CHAPTER VIII 

Methods of Cylinder Construction — Block Castings — Influence on Crank- 
Shaft Design — Combustion Chamber Design 1 — Bore and Stroke Ratio 
— Meaning of Piston Speed — Advantage of Off-Set Cylinders — 
Valve Location of Vital Import — Valve Installation Practice — Valve 
Design and Construction — Valve Operation — Methods of Driving 
Cam-Shaft — Valve Springs — Valve Timing — Blowing Back — Lead 
Given Exhaust Valve — Exhaust Closing, Inlet Opening — Closing the 
Inlet Valve — Time of Ignition — How an Engine is Timed — Gnome 
"Monosoupape" Valve Timing — Springless Valves — Four Valves 
per Cylinder 233-286 



Contents 13 

CHAPTER IX 

FACES 

Constructional Details of Pistons — Aluminum Cylinders and Pistons — 
Piston Eing Construction — Leak Proof Piston Rings — Keeping Oil 
Out of Combustion Chamber — Connecting Rod Forms — Connecting 
Rods for Vee Engines — Cam-Shaft and Crank-Shaft Designs — Ball 
Bearing Crank-Shafts — Engine Base Construction .... 287-323 

CHAPTER X 

Power Plant Installation — Curtiss OX-2 Engine Mounting and Operating 
Rules — Standard S. A. E. Engine Bed Dimensions — Hall-Scott 
Engine Installation and Operation — Fuel System Rules — Ignition 
System — Water System — Preparations to Start Engine — Mounting 
Radial and Rotary Engines — Practical Hints to Locate Engine 
Troubles — All Engine Troubles Summarized — Location of Engine 
Troubles Made Easy 324-375 

CHAPTER XI 

Tools for Adjusting and Erecting — Forms of Wrenches — Use and Care 
of Files — Split Pin Removal and Installation — Complete Chisel Set 
— Drilling Machines — Drills, Reamers, Taps and Dies — ^Measuring 
Tools — Micrometer Calipers and Their Use — Typical Tool Outfits — 
Special Hall-Scott Tools — Overhauling Airplane Engines — Taking 
Engine Down — Defects in Cylinders — Carbon Deposits, Cause and 
Prevention — Use of Carbon Scrapers — Burning Out Carbon with 
Oxygen — Repairing Scored Cylinders — Valve Removal and Inspec- 
tion — Reseating and Truing Valves — Valve Grinding Processes — 
Depreciation in Valve Operating System — Piston Troubles — Piston 
Ring Manipulation — Fitting Piston Rings — Wrist-Pin Wear — In- 
spection and Refitting of Engine Bearings — Scraping Brasses to Fit 
— Fitting Connecting Rods — Testing for Bearing Parallelism — Cam- 
shafts and Timing Gears — Precautions in Reassembling Parts . 376-456 

CHAPTER XII 

Aviation Engine Types — Division in Classes — Anzani Engines — Canton 
and Unne Engine — Construction of Gnome Engines — "Monosou- 
pape" Gnome — German "Gnome" Type — Le Rhone Engine — 
Renault Air-Cooled Engine — Simplex Model "A" Hispano-Suiza — 
Curtiss Aviation Motors — Thomas-Morse Model 88 Engine — Duesen- 
berg Engine — Aeromarine Six-Cylinder — Wisconsin Aviation 
Engines — Hall-Scott Engines — Mercedes Motor — Benz Motor — 
Austro-Daimler Engine — Sunbeam-Coatalen — Indicating and Meas- 
uring Instruments — Air Starting Systems — Electric Starting — Bat- 
tery Ignition 457-571 

INDEX 573 



AVIATION ENGINES 
DESIGN— CONSTRUCTION- REPAIR 

CHAPTER I 

Brief Consideration of Aircraft Types — Essential Requirements of 
Aerial Motors — Aviation Engines Must Be Light — Factors In- 
fluencing Power Needed — Why Explosive Motors Ar? Best — His- 
torical — Main Types of Internal Combustion Engines. 

BRIEF CONSIDERATION OF AIRCRAFT TYPES 

The conquest of the air is one of the most stupendous 
achievements of the ages. Human flight opens the sky- 
to man as a new road, and because it is a road free of all 
obstructions and leads everywhere, affording the shortest 
distance to any place, it offers to man the prospect of 
unlimited freedom. The aircraft promises to span con- 
tinents like railroads, to bridge seas like ships, to go over 
mountains and forests like birds, and to quicken and 
simplify the problems of transportation. While the actual 
conquest of the air is an accomplishment just being real- 
v ized in our days, the idea and yearning to conquer the air 
are old, possibly as old as intellect itself. The myths of 
different races tell of winged gods and flying men, and 
show that for ages to fly was the highest conception of 
the sublime. No other agent is more responsible for sus- 
tained flight than the internal combustion motor, and it 
was only when this form of prime mover had been fully 
developed that it was possible for man to leave the ground 
and alight at will, not depending upon the caprices of 
the winds or lifting power of gases as with the balloon. 
It is safe to say that the solution of the problem of flight 
would have been attained many years ago if the proper 
source of power had been available as all the essential 

17 



18 Aviation Engines 

elements of the modern aeroplane and dirigible balloon, 
other than the power plant, were known to early philoso- 
phers and scientists. 

Aeronautics is divided into two fundamentally differ- 
ent branches — aviatics and aerostatics. The first com- 
prises all types of aeroplanes and heavier than air flying 
machines such as the helicopters, kites, etc.; the second 
includes dirigible balloons, passive balloons and all craft 
which rise in the air by utilizing the lifting force of gases. 
Aeroplanes are the only practical form of heavier- than-air 
machines, as the helicopters (machines intended to be 
lifted directly into the air by propellers, without the sus- 
taining effect of planes), and ornithopters, or flapping 
wing types, have not been thoroughly developed, and in 
fact, there are so many serious mechanical problems to 
be solved before either of these types of air craft will 
function properly that experts express grave doubts re- 
garding the practicability of either. Aeroplanes are di- 
vided into two main types — monoplanes or single surface 
forms, and bi-planes or machines having two sets of lift- 
ing surfaces, one suspended over the other. A third type, 
the triplane, is not very widely used. 

Dirigible balloons are divided into three classes: the 
rigid, the semi-rigid, and the non-rigid. The rigid has a 
frame or skeleton of either wood or metal inside of the 
bag, to stiffen it; the semi-rigid is reinforced by a wire 
net and metal attachments; while the non-rigid is just a 
bag filled with gas. The aeroplane, more than the dirigible 
and balloon, stands as the emblem of the conquest of the 
air. Two reasons for this are that power flight is a real 
conquest of the air, a real victory over the battling ele- 
ments; secondly, because the aeroplane, or any flying ma- 
chine that may follow, brings air travel within the reach 
of everybody. In practical development, the dirigible may 
be the steamship of the air, which will render invaluable 
services of a certain kind, and the aeroplane will be the 
automobile of the air, to be used by the multitude, perhaps 
for as many purposes as the automobile is now being used. 



Aviation Motor Requirements 19 

ESSENTIAL REQUIREMENTS OF AERIAL MOTORS 

One of the marked features of aircraft development has 
been the effect it has had upon the refinement and perfec- 
tion of the internal combustion motor. Without question 
gasoline-motors intended for aircraft are the nearest to 
perfection of any other type yet evolved. Because of the 
peculiar demands imposed upon the aeronautical motor it 
must possess all the features of reliability, economy and 
efficiency now present with automobile or marine engines 
and then must have distinctive points of its own. Owing 
to the unstable nature of the medium through which it is 
operated and the fact that heavier-than-air machines can 
maintain flight only as long as the power plant is func- 
tioning properly, an airship motor must be more reliable 
than any used on either land or water. AVhile a few 
pounds of metal more or less makes practically no dif- 
ference in a marine motor and has very little effect upon 
the speed or hill-climbing ability of an automobile, an 
airship motor must be as light as it is possible to make 
it because every pound counts, whether the motor is to be 
fitted into an aeroplane or in a dirigible balloon. 

Airship motors, as a rule, must operate constantly at 
high speeds in order to obtain a maximum power delivery 
with a minimum piston displacement. In automobiles, or 
motor boats, motors are not required to run constantly at 
their maximum speed. Most aircraft motors must func- 
tion for extended periods at speed as nearly the maximum 
as possible. Another thing that militates against the air- 
craft motor is the more or less unsteady foundation to 
which it is attached. The necessarily light framework of the 
aeroplane makes it hard for a motor to perform at maxi- 
mum efficiency on account of the vibration of its foundation 
while the craft is in flight. Marine and motor car engines, 
while not placed on foundations as firm as those provided 
for stationary power plants, are installed on bases of much 
more stability than the light structure of an aeroplane. 
The aircraft motor, therefore, must be balanced to a nicety 



20 Aviation Engines 

and must run steadily under the most unfavorable con- 
ditions. 

AERIAL MOTORS MUST BE LIGHT 

The capacity of light motors designed for aerial work 
per unit of mass is surprising to those not fully con- 
versant with the possibilities that a thorough knowledge 
of proportions of parts and the use of special metals 
developed by the automobile industry make possible. Ac- 
tivity in the development of light motors has been more 
pronounced in France than in any other country. Some 
of these motors have been complicated types made light 
by the skillful proportioning of parts, others are of the 
refined simpler form modified from current automobile 
practice. There is a tendency to depart from the freakish 
or unconventional construction and to adhere more closely 
to standard forms because it is necessary to have the parts 
of such size that every quality making for reliability, 
efficiency and endurance are incorporated in the design. 
Aeroplane motors range from two cylinders to forms hav- 
ing fourteen and sixteen cylinders and the arrangement 
of these members varies from the conventional vertical 
tandem and opposed placing to the V form or the more 
unusual radial motors having either fixed or rotary cyl- 
inders. The weight has been reduced so it is possible to 
obtain a complete power plant of the revolving cylinder 
air-cooled type that will not weigh more than three pounds 
per actual horse-power and in some cases less than this. 

If we give brief consideration to the requirements of 
the aviator it will be evident that one of the most im- 
portant is securing maximum power with minimum mass, 
and it is desirable to conserve all of the good qualities 
existing in standard automobile motors. These are cer- 
tainty of operation, good mechanical balance and uniform 
delivery of power — fundamental conditions which must be 
attained before a power plant can be considered practical. 
There are in addition, secondary considerations, none the 
less desirable, if not absolutely essential. These are min- 



Factors Influencing Power Needed 21 

imum consumption of fuel and lubricating oil, which is 
really a factor of import, for upon the economy depends 
the capacity and flying radius. As the amount of liquid 
fuel must be limited the most suitable motor will be that 
which is powerful and at the same time economical. An- 
other important feature is to secure accessibility of com- 
ponents in order to make easy repair or adjustment of 
parts possible. It is possible to obtain sufficiently light- 
weight motors without radical departure from established 
practice. Water-cooled power plants have been designed 
that will weigh but four or five pounds per horse-power 
and in these forms we have a practical power plant 
capable of extended operation. 

FACTORS INFLUENCING POWER NEEDED 

Work is performed whenever an object is moved against 
a resistance, and the amount of work performed depends 
not only on the amount of resistance overcome but also 
upon the amount of time utilized in accomplishing a given 
task. Work is measured in horse-power for convenience. 
It will take one horse-power to move 33,000 pounds one 
foot in one minute or 550 pounds one foot in one second. 
The same work would be done if 330 pounds were moved 
100 feet in one minute. It requires a definite amount of 
power to move a vehicle over the ground at a certain 
speed, so it must take power to overcome resistance of 
an airplane in the air. Disregarding the factor of air 
density, it will take more power as the speed increases 
if the weight or resistance remains constant, or more 
power if the speed remains constant and the resistance 
increases. The airplane is supported by air reaction un- 
der the planes or lifting surfaces and the value of this 
reaction depends upon the shape of the aerofoil, the 
amount it is tilted and the speed at which it is drawn 
through the air. The angle of incidence or degree of 
wing tilt regulates the power required to a certain degree 
as this affects the speed of horizontal flight as well as the 
resistance. Eesistance may be of two kinds, one that is 



22 Aviation Engines 

necessary and the other that it is desirable to reduce to 
the lowest point possible. There is the wing resistance 
and the sum of the resistances of the rest of the machine 
such as fuselage, struts, wires, landing gear, etc. If we 
assume that a certain airplane offered a total . resistance 
of 300 pounds and we wished to drive it through the air 
at a speed of sixty miles per hour, we can find the horse- 
power needed by a very simple computation as follows: 
The product of 

300 pounds resistance times speed of 88 feet 
per second times 60 seconds in a minute 

... . _ ■ _. _ , ; = H.P. needed. 

divided by 33,000 foot pounds per minute 

in one horse-power 

The result is the horse-power needed, or 

300 X 88 X 60 

= 48 H.P. ' 

33,000 

Just as it takes more power to climb a hill than it does 
to run a car on the level, it takes more power to climb 
in the air with an airplane than it does to fly on the level. 
The more rapid the climb, the more power it will take. 
If the resistance remains 300 pounds and it is necessary 
to drive the plane at 90 miles per hour, we merely sub- 
stitute proper values in the above formula and we have 

300 pounds times 132 feet per second times 60 
seconds in a minute 

: = 72 H.P. 

33,000 foot pounds per minute in one 
horse-power 

The same results can be obtained by dividing the product 
of the resistance in pounds times speed in feet per second 
by 550, which is the foot-pounds of work done in one 
second to equal one horse-power. Naturally, the amount 
of propeller thrust measured in pounds necessary to drive 
an airplane must be greater than the resistance by a sub- 
stantial margin if the plane is to fly and climb as well. 



Computations for Horse-Power Needed 23 



The following formulae were given in "The Aeroplane" 
of London and can be nsed to advantage by those desiring 
to make computations to ascertain power requirements: 
The thrust of the propeller depends on the power of 




L= Liff = Weight = W 

D = Drift 

R= Reaction 

a = Angle of Incidence 



Tan a =-£,D= TanocL 




Pr- Momentum = M 

Pr 2 Jt = Work 

Pr 2 Jt = Work M in. 



60x75 =H ' R orm En 9 lish 
Pr2 7tR 



2rJt 




Fig. 1. — Diagrams Illustrating Computations for Horse-Power Eequired for 

Airplane Flight. 



24s Aviation Engines 

the motor, and on the diameter and pitch of the propeller. 
If the required thrust to a certain machine is known, the 
calculation for the horse-power of the motor shoulol be an 
easy matter. 

The required thrust is the sum of three different " re- 
sistances.' ' The first is the "drift" (dynamical head re- 
sistance of the aerofoils), i.e., tan a X lift (L), lift being 
equal to the total weight of machine (W) for horizontal 
flight and a equal to the angle of incidence. Certainly we 
must take the tan a at the maximum K y value for minimum 
speed, as then the drift is the greatest (Fig. 1, A). 

Another method for finding the drift is D = K X AV 2 , 
when we take the drift again so as to be greatest. 

The second "resistance" is the total head resistance 
of the machine, at its maximum velocity. And the third 
is the thrust for climbing. The horse-power for climbing 
can be found out in two different ways. I first propose 
to deal with the method, where we find out the actual 
horse-power wanted for a certain climbing speed to our 
machine, where 

climbing speed/sec. X W 

H.P. = 

550 

In this case we know already the horse-power for climb- 
ing, and we can proceed with our calculation. 

With the other method we shall find out the "thrust" 
in pounds or kilograms wanted for climbing and add it 
to drift and total head resistance, and we shall have the 
total "thrust" of our machine and we shall denote it 
with T, while thrust for climbing shall be Tc. 

The following calculation is at our service to find out 

VcXW 

this thrust for climbing = H.P., 

550 

H.P. X 550 

thence Vc = (1) 

W 



Computations for Horse-Power Needed 25 

To XV 

H.P. = , then from 

550 

To XV 
ys 550 

550 To XV VcXW 

(1) Vc = = , thence, To = 

WW V 

Whether T means drifts, head resistance and thrust 
for climbing, or drift and head resistance only, the fol- 
lowing calculation is the same, only in the latter case, of 
course, we must add the horse-power required for climb- 
ing to the result to obtain the total horse-power. 

Now, when we know the total thrust, we shall find the 
horse-power in the following manner: 

Pr2%R 

"We know that the H.P. = in kilograms, or in 

75 X 60 

Pr2*R 

English measure, H.P. = (Fig. 1, B) 

33,000 

where P = pressure in klgs. or lbs. 

r = radius on which P is acting. 
R = Eevolution/min. 

MP. 2 7u 

When B Xr = M, then H.P. = , thence, 

4,500 

H.P. X 4,500 716.2 H.P. 

M = = in meter kilograms, 

E2x R 

H.P. 33,000 5253.1 H.P. 

or in English system M = = in foot 

R2k R 

pounds. 

Now the power on the circumference of the propeller 

M 

will be reduced by its radius, so it will be — = p. A part 

r 



26 Aviation Engines 

of p will be used for counteracting the air and bearing fric- 
tion, so that the total power on the circumference of the 

M 

propeller will be — X *) = P where r\ is the mechanical 
r 

efficiency of the propeller. Now = T, where a is taken 

tan a 

on the tip of the propeller. 

I take a at the tip, but it can be taken, of course, at any 

M 

point, but then in equation p = — , r must be taken only up 

r 

to this point, and not the whole radius ; but it is more coin- 
Pitch 
fortable to take it at the tip, as tan a = (Fig. 1, C). 

r2% 

Now we can write up the equation of the thrust : 

716.2 H.P. Yj 5253.1 H.P. yj 

T = , or in English measure 

R r tan a R r tan a 

T XRXrtana 

thence H.P. = , or in English measure 

716.2 r) 

T X R X rtana 



5253.1 y] 

The computations and formulae given are of most value 
to the student engineer rather than matters of general 
interest, but are given so that a general idea may be 
secured of how airplane design influences power needed 
to secure sustained flight. It will be apparent that the 
resistance of an airplane depends upon numerous con- 
siderations of design which require considerable research 
in aerodynamics to determine accurately. It is obvious 
that the more resistance there is, the' more power needed 
to fly at a given speed. Light monoplanes have been 
flown with as little as 15 horse-power for short distances, 



Why Explosive Motors Are Best 27 

but most planes now built use engines of 100 horse-power 
or more. Giant airplanes have been constructed having 
2,000 horse-power distributed in four power units. The 
amount of power provided for an airplane of given design 
varies widely as many conditions govern this, but it will 
range from approximately one horse-power to each 8 
pounds weight in the case of very light, fast machines 
to one horse-power to 15 or 18 pounds of the total weight 
in the case of medium speed machines. The development 
in airplane and power plant design is so rapid, however, 
that the figures given can be considered only in the light 
of general averages rather than being typical of current 
practice. 

WHY EXPLOSIVE MOTOES ARE BEST 

Internal combustion engines are best for airplanes and 
all types of aircraft for the same reasons that they are 
universally used as a source of power for automobiles. 
The gasoline engine is the lightest known form of prime 
mover and a more efficient one than a steam engine, es- 
pecially in the small powers used for airplane propul- 
sion. It has been stated that by very careful designing 
a steam plant and engine could be made that would be 
practical for airplane propulsion, but even with the latest 
development it is doubtful if steam power can be utilized 
in aircraft to as good advantage as modern gasoline- 
engines are. While the steam-engine is considered very 
much simpler than a gas-motor, the latter is much more 
easily mastered by the non-technical aviator and certainly 
requires less attention. A weight of 10 pounds per horse- 
power is possible in a condensing steam plant but this 
figure is nearly double or triple what is easily secured 
with a gas-motor which may weigh but 5 pounds per horse- 
power in the water cooled forms and but 2 or 3 pounds 
in the air-cooled types. The fuel consumption is twice 
as great in a steam-power plant (owing to heat losses) 
as would be the case in a gasoline engine of equal power 
and much Ip.ss weight. 



28 Aviation Engines 

The internal-combustion engine has come seemingly 
like an avalanche of a decade ; but it has come to stay, 
to take its well-deserved position among the powers for 
aiding labor. Its ready adaptation to road, aerial and 
marine service has made it a wonder of the age in the 
development of speed not before dreamed of as a possi- 
bility; yet in so short a time, its power for speed has 
taken rank on the common road against the locomotive 
on the rail with its century's progress. It has made aerial 
navigation possible and practical, it furnishes power for 
all marine craft from the light canoe to the transatlantic 
liner. It operates the machine tools of the mechanic, tills 
the soil for the farmer and provides healthful recreation 
for thousands by furnishing an economical means of trans- 
port by land and sea. It has been a universal mechanical 
education for the masses, and in its present forms repre- 
sents the great refinement and development made possible 
by the concentration of the world's master minds on the 
problems incidental to internal combustion engineering. 

HISTOKICAL 

Although the ideal principle of explosive power was 
conceived some two hundred years ago, at which time 
experiments were made with gunpowder as the explosive 
element, it was not until the last years of the eighteenth 
century that the idea took a patentable shape, and not 
until about 1826 (Brown's gas-vacuum engine) that a fur- 
ther progress was made in England by condensing the 
products of combustion by a jet of water, thus creating 
a partial vacuum. 

Brown's was probably the first explosive engine that 
did real work. It was clumsy and unwieldy and was soon 
relegated to its place among the failures of previous ex- 
periments. No approach to active explosive effect in a 
cylinder was reached in practice, although many ingenious 
designs were described, until about 1838 and the following 
years. Barnett's engine in England was the first attempt 
to compress the charge before exploding. From this tme 



Why Explosive Motors Are Best 29 

on to about 1860 many patents were issued in Europe and 
a few in the United States for gas-engines, but the prog- 
ress was slow, and its practical introduction for power 
came with spasmodic effect and low efficiency. From 1860 
on, practical improvement seems to have been made, and 
the Lenoir motor was produced in France and brought 
to the United States. It failed to meet expectations, and 
was soon followed by further improvements in the Hugon 
motor in France (1862), followed by Beau de Rocha's 
four-cycle idea, which has been slowly developed through 
a long series of experimental trials by different inventors. 
In the hands of Otto and Langdon a further progress was 
made, and numerous patents were issued in England, 
France, and Germany, and followed up by an increasing 
interest in the United States, with a few patents. 

From 1870 improvements seem to have advanced at 
a steady rate, and largely in the valve-gear and precision 
of governing for variable load. The early idea of the ne- 
cessity of slow combustion was a great drawback in the 
advancement of efficiency, and the suggestion of de Rocha 
in 1862 did not take root as a prophetic truth until many 
failures and years of experience had taught the funda- 
mental axiom that rapidity of action in both combustion 
and expansion was the basis of success in explosive motors. 

With this truth and the demand for small and safe 
prime movers, the manufacture of gas-engines increased 
in Europe and America at a more rapid rate, and improve- 
ments in perfecting the details of this cheap and efficient 
prime mover have finally raised it to the dignity of a 
standard motor and a dangerous rival of the steam-engine 
for small and intermediate powers, with a prospect of 
largely increasing its individual units to many hundred, 
if not to the thousand horse-power in a single cylinder. 
The unit size in a single cylinder has now reached to about 
700 horse-power and by combining cylinders in the same 
machine, powers of from 1,500 to 2,000 horse-power are 
now available for large power-plants. 



30 Aviation Engines 

MAIN TYPES OF INTERNAL-COMBUSTION ENGINES 

This form of prime mover has been built in so many 
different types, all of which have operated with some 
degree of success that the diversity in form will not be 
generally appreciated unless some attempt is made to 
classify the various designs that have received practical 
application. Obviously the same type of engine is not 
universally applicable, because each class of work has 
individual peculiarities which can best be met by an en- 
gine designed with the peculiar conditions present in view. 
The following tabular synopsis will enable the reader to 
judge the extent of the development of what is now the 
most popular prime mover for all purposes. 

A. Internal Combustion (Standard Type) 

1. Single Acting (Standard Type) 

2. Double Acting (For Large Power Only) 

3. Simple (Universal Form) 

4. Compound (Rarely -Used) 

5. Reciprocating Piston (Standard Type) 

6. Turbine (Revolving Rotor, not fully devel- 

oped) 

Al. Two-Stroke Cycle 

a. Two Port 

b. Three Port 

c. Combined Two and Three Port 

d. Fourth Port Accelerator 

e. Differential Piston Type 

f. Distributor Valve System 

A2. Four-Stroke Cycle 

a. Automatic Inlet Valve 

b. Mechanical Inlet Valve 

c. Poppet or Mushroom Valve 

d. Slide Valve 

d 1. Sleeve Valve 

d 2. Reciprocating Ring Valve 

d 3. Piston Valve 



Gas Engine Types Classified 31 

e. Eotary Valves 

e 1. Disc 

e 2. Cylinder or Barrel 

e 3. Single Cone 

e 4. Double Cone 

f. Two Piston (Balanced Explosion) 

g. Eotary Cylinder, Fixed Crank (Aerial) 

h. Fixed Cylinder, Eotary Crank (Standard 
Type) 

4 

A3. Six-Stroke Cycle 

B. External Combustion (Practically Obsolete) 

a. Turbine, Eevolving Eotor 

b. Eeciprocating Piston 

CLASSIFICATION BY CYLINDER ARRANGEMENT 

Single Cylinder 

a. Vertical 

b. Horizontal 

c. Inverted Vertical 

Double Cylinder 

a. Vertical 

b. Horizontal (Side by Side) 

c. Horizontal (Opposed) 

d. 45 to 90 Degrees V (Angularly Disposed) 

e. Horizontal Tandem (Double Acting) 

Three Cylinder 

a. Vertical 

b. Horizontal 

c. Eotary (Cylinders Spaced at 120 Degrees) 

d. Eadially Placed (Stationary Cylinders) 

e. One Vertical, One Each Side at an Angle 

f. Compound (Two High Pressure, One Low 

Pressure) 

Four Cylinder 

a. Vertical 

b. Horizontal (Side by Side) 






32 Aviation Engines 

c. Horizontal (Two Pairs Opposed) 

d. 45 to 90 Degrees V 

e. Twin Tandem (Double Acting) 

Five Cylinder 

a. Vertical (Five Throw Crankshaft) 

b. Radially Spaced at 72 Degrees (Stationary) 

c. Radially Placed Above Crankshaft (Station- 

ary) 

d. Placed Around Rotary Crankcase (72 Degrees 

Spacing) 

Six Cylinder 

a. Vertical 

b. Horizontal (Three Pairs Opposed) 

c. 45 to 90 Degrees V 

Seven Cylinder 

a. Equally Spaced (Rotary) 

Eight Cylinder 

a. Vertical 

b. Horizontal (Four Pairs Opposed) 

c. 45 to 90 Degrees V 

Nine Cylinder 

a. Equally Spaced (Rotary) 

Twelve Cylinder 

a. Vertical 

b. Horizontal (Six Pairs Opposed) 

c. 45 to 90 Degrees V 

Fourteen Cylinder 
a. Rotary 

Sixteen Cylinder 

a. 45 to 90 Degrees V 

b. Horizontal (Eight Pairs Opposed) 

Eighteen Cylinder 
a. Rotary Cylinder 




Two -Cylinder^ Double Acting, Tour Cycle Engine for Blast Furnace Gas Fuel 

Weight 600- Pounds per Horsepower 
Very slow speed, made in sizes up+o 2000 Horsepower. 60+o 100 R.P.M. 




Two Cylinder Opposed Gas Engine - 150 +0 650 Horsepower Sizes-. 
500 +0 600 Pounds per Horsepower. 90 to 100 R. P. M. 




Stationary Diesel Engine ed Stationary Gas Engine 

450 to 500 Pounds per Approximately four Cycle-Two Cylinder 
Horsepower ZOO R.P.M. 500 Pounds perHorsepower 



Fig. 2. — Plate Showing Heavy, Slow Speed Internal Combustion Engines 
Used Only for Stationary Power in Large Installations Giving Weight 
to Horse-Power Ratio. 

33 




Four Cylinder Diesel Engine for Marine Use 
Z50 Pounds perHorsepower 



ffFi 





Two- Cycle Marine Engine 
50-100 Pounds per Horsepower 
600+0 600 R.P M- 



Single Cylinder VerHcal Farm Engine 
150 Pounds per Horsepower- Speed 400 R RM. 





Two Cylinder Four Cycle Tractor Engtne 
15 Pounds per Horsepower 
800 +o 1 000. R.F.M. 



Four-CyFtnder Four Cycle Automobile PowerPlant 
Weighsabout 2.5 Pounds per Horsepower 
IZOO to Z000 R.P. M. 



Fig. 3. — Various Forms of Internal Combustion Engines Showing Decrease 
in Weight to Horse-Power Ratio with Augmenting Speed of Rotation. 

34 




Eight Cylinder Vee'Automobile Engine 
15+0 18 Pounds per Horse power 
Speeds 1500 +O2000R P.M. 



Two CylinderAirCooled Motorcycle 

Engine weigh+s 8-10 Pounds Horsepower 

Speed 3000 R. P.M. 




Six, Eight or Twelve Cylinder Water Cooled Aviation Engine, TandemorV Form 
4 +o 6 Pounds per Horsepower 
Speed 1500 R. P. M. Direct Coupled - 2000 R P.M. Geared Drive 




Fourteen or Eighteen Cylinder 
Seven or Nine Cylinder Revolvj'nq Revolving Air Cooled Avia+ion Engine 

Air Cooled ^ Speed 1200 R.P.M. 

Speed IZOO R.P.M.Z.8 Pounds per Horsepower Z Pounds per Horsepower 



Fig. 4. — Internal Combustion Engine Types of Extremely Fine Construction 
and Refined Design, Showing Great Power Outputs for Very Small 
Weight, a Feature Very Much Desired in Airplane Power Plants. 

35 



36 Aviation Engines 

Of all the types enumerated above engines having less 
than eight cylinders are the most popular in everything 
but aircraft work. The four-cylinder vertical is without 
doubt the most widely used of al) types owing to the 
large number employed as automobile power plants. 
Stationary engines in small and medium powers are in- 
variably of the single or double form. Three-cylinder 
engines are seldom used at the present time, except in 
marine work and in some stationary forms. Eight- and 
twelve-cylinder motors have received but limited appli- 
cation and practically always in automobiles, racing motor 
boats or in aircraft. The only example of a fourteen- 
cylinder motor to be used to any extent is incorporated 
in aeroplane construction. This is also true of the six- 
teen- and eighteen-cylinder forms and of twenty-four- 
cylinder engines now in process of development. 

The duty an engine is designed for determines the 
weight per horse-power. High powered engines intended 
for steady service are always of the slow speed type and 
consequently are of very massive construction. Various 
forms of heavy duty type stationary engines are shown 
at Fig. 2. Some of these engines may weigh as much as 
600 pounds per horse-power. A further study is possible 
by consulting data given on Figs. 3 and 4. As the crank- 
shaft speed increases and cylinders are multiplied the 
engines become lighter. While the big stationary power 
plants may run for years without attention, airplane en- 
gines require rebuilding after about 60 to 80 hours air 
service for the fixed cylinder types and 40 hours or less 
for the rotary cylinder air-cooled forms. There is evi- 
dently a decrease in durability and reliability as the 
weight is lessened. These illustrations also permit of 
obtaining a good idea of the variety of forms internal 
combustion engines are made in. 



CHAPTER II 

Operating Principles of Two- and Four-Stroke Engines — Four-cycle 
Action — Two-cycle Action — Comparing Two- and Four-cycle Types 
— Theory of Gas and Gasoline Engine — Early Gas-Engine Forms — 
Isothermal Law — Adiabatic Law — Temperature Computations — 
Heat and Its Work — Conversion of Heat to Power — Requisites 
for Best Power Effect. 

OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE 
CYCLE ENGINES 

Before discussing the construction of the various forms 
of internal combustion engines it may be well to describe 
the operating cycle of the types most generally used. 
The two-cycle engine is the simplest because there are no 
valves in connection with the cylinder, as the gas is in- 
troduced into that member and expelled from it through 
ports cored into the cylinder walls. These are covered by 
the piston at a certain portion of its travel and uncov- 
ered at other parts of its stroke. In the four-cycle engine 
the explosive gas is admitted to the cylinder through a 
port at the head end closed by a valve, while the exhaust 
gas is expelled through another port controlled in a simi- 
lar manner. These valves are operated by mechanism 
distinct from the piston. 

The action of the four-cycle type may be easily under- 
stood if one refers to illustrations at Figs. 5 and 6. It 
is called the "four-stroke engine" because the piston must 
make four strokes in the cylinder for each explosion or 
power impulse obtained. The principle of the gas-engine 
of the internal combustion type is similar to that of a 
gun, i.e., power is obtained by the rapid combustion of 
some explosive or other quick burning substance. The 
bullet is driven out of the gun barrel by the pressure of 
the gas evolved when the charge of powder is ignited. 
The piston or movable element of the gas-engine is driven 

37 



38 



Aviation Engines 



from the closed or head end to the crank end of the 
cylinder by a similar expansion of gases resulting from 
combustion. The first operation in firing a gnn or secur- 
ing an explosion in the cylinder of the gas-engine is to 



Inlet Pipe 



1. Cylinder Filling with Gas. 



2. Piston Compressing Gas. 



Inlet Value 
shown Open 

Exhaust Value. 
Closed 

Exhaust Pipe. 
Value Spring- 



Cylinder Filled with 
' Combustible Gas 



^S> Cooling Flanges 



•Piston Ascending 




1. Powder Inserted. 



2. Powder Compressed. 



Fig. 5. — Outlining First Two Strokes of Piston in Four-Cycle Engine. 

fill the combustion space with combustible material. This 
is done by a down stroke of the piston during which time 
the inlet valve opens to admit the gaseous charge to the 
cylinder interior. This operation is shown at Fig. 5, A. 
The second operation is to compress this gas which is 
done by an upward stroke of the piston as shown at Fig. 



Internal Combustion Engine Action 



39 



5, B. When the top of the compression stroke is reached, 
the gas is ignited and the piston is driven down toward 
the open end of the cylinder, as indicated at Fig. 6, C. The 
fourth operation or exhaust stroke is performed by the 



8. Compressed Gas Exploded. 



4. Inert Gases Exhausted. 



Both Values Closed 



Spark Plug 
Cooling Flanges 




3. Powder Exploded. 



4. Powder Gas Exhausted. 



Fig. 6. — Outlining Second Two Strokes of Piston in Four-Cycle Engine. 

return upward movement of the piston as shown at Fig. 
6, D during which time the exhaust valve is opened to 
permit the burnt gases to leave the cylinder. As soon 
as the piston reaches the top of its exhaust stroke, the 
energy stored in the fly-wheel rim during the power stroke 
causes that member to continue revolving and as the piston 



40 



Aviation Engines 




Fig. 7.— Sectional View of L Head Gasoline Engine Cylinder Showing 
Piston Movements During Four-Stroke Cycle. 



How Two-Stroke Cycle Engine Works 41 

again travels on its down stroke the inlet valve opens and 
admits a charge of fresh gas and the cycle of operations 
is repeated. 

The illustrations at Fig. 7 show how the various cycle 
functions take place in an L head type water cooled cyl- 
inder engine. The sections at A and C are taken through 
the inlet valve, those at B and D are taken through the 
exhaust valve. 

The two-cycle engine works on a different principle, as 
while only the combustion chamber end of the piston is 
employed to do useful work in the four-cycle engine, both 
upper and lower portions are called upon to perform the 
functions necessary to two-cycle engine operation. In- 
stead of the gas being admitted into the cylinder as is the 
case with the four-stroke engine, it is first drawn into the 
engine base where it receives a preliminary compression 
prior to its transfer to the working end of the cylinder. 
The views at Fig. 8 should indicate clearly the operation 
of the two-port two-cycle engine. At A the piston is 
seen reaching the top of its stroke and the gas above the 
piston is being compressed ready for ignition, while the 
suction in the engine base causes the automatic valve to 
open and admits mixture from the carburetor to the 
crank case. When the piston reaches the top of its stroke, 
the compressed gas is ignited and the piston is driven 
down on the power stroke, compressing the gas in the 
engine base. 

When the top of the piston uncovers the exhaust port 
the flaming gas escapes because of its pressure. A down- 
ward movement of the piston uncovers the inlet port 
opposite the exhaust and permits the fresh gas to bypass 
through the transfer passage from the engine base to the 
cylinder. The conditions with the intake and exhaust 
port fully opened are clearly shown at Fig. 8, C. The 
deflector plate on the top of the piston directs the enter- 
ing fresh gas to the top of the cylinder and prevents the 
main portion of the gas stream from flowing out through 
the open exhaust port. On the next upstroke of the piston 



42 



Aviation Engines 





o 

p» 
6 

H 

bo 

S 

o 
CO 



How Two-Stroke Cycle Engine Works 



43 



c<fe- 





A 
H 

bJD 
C 

'2 




44 Aviation Engines 

the gas in the cylinder is compressed and the inlet valve 
opened, as shown at A to permit a fresh charge to enter 
the engine base. 

The operating principle of the three-port, two-cycle 
engine is practically the same as that previously described 
with the exception that the gas is admitted to the crank- 
case through a third port in the cylinder wall, which is 
uncovered by the piston when that member reaches the 
end of its upstroke. The action of the three-port form 
can be readily ascertained by studying the diagrams given 
at Fig. 9. Combination two- and three-port engines have 
been evolved and other modifications made to improve the 
action. 

THE TWO-CYCLE AND FOUR-CYCLE TYPES 

In the earlier years of explosive-motor progress was 
evolved the two types of motors in regard to the cycles 
of their operation. The early attempts to perfect the 
two-cycle principle were for many years held in abeyance 
from the pressure of interests in the four-cycle type, until 
its simplicity and power possibilities were demonstrated 
by Mr. Dugald Clerk in England, who gave the principles 
of the two-cycle motor a broad bearing leading to im- 
mediate improvements in design, which has made further 
progress in the United States, until at the present time 
it has an equal standard value as a motor-power in some 
applications as its ancient rival the four-cycle or Otto 
type, as demonstrated by Beau de Rocha in 1862. 

Thermodynamically, the methods of the two types are 
equal as far as combustion is concerned, and compression 
may favor in a small degree the four-cycle type as well 
as the purity of the charge. The cylinder volume of the 
two-cycle motor is much smaller per unit of power, and 
the enveloping cylinder surface is therefore greater per 
unit of volume. Hence more heat is carried off by the 
jacket water during compression, and the higher com- 
pression available from this tends to increase the economy 
during compression which is lost during expansion. 



Two- and Four-Stroke Cycles Compared 45 

From the above considerations it may be safely stated 
that a lower temperature and higher pressure of charge 
at the beginning of compression is obtained in the two- 
cycle motor, greater weight of charge and greater specific 
power of higher compression resulting in higher thermal 
efficiency. The smaller cylinder for the same power of 
the two-cycle motor gives less friction surface per impulse 
than of the other type; although the crank-chamber pres- 
sure may, in a measure, balance the friction of the four- 
cycle type. Probably the strongest points in favor of the 
two-cycle type are the lighter fly-wheel and the absence 
of valves and valve gear, making this type the most simple 
in construction and the lightest in weight for its developed 
power. Yet, for the larger power units, the four-cycle 
type will no doubt always maintain the standard for 
efficiency and durability of action. 

The distribution of the charge and its degree of mix- 
ture with the remains of the previous explosion in the 
clearance space, has been a matter of discussion for both 
types of explosive motors, with doubtful results. In Fig. 
10, A we illustrate what theory suggests as to the distribu- 
tion of the fresh charge in a two-cycle motor, and in Fig. 
10, B what is the probable distribution of the mixture when 
the piston starts on its compressive stroke. The arrows 
show the probable direction of flow of the fresh charge 
and burnt gases at the crucial moment. 

In Fig. 10, C is shown the complete out-sweep of the 
products of combustion for the full extent of the piston 
stroke of a four-cycle motor, leaving only the volume of 
the clearance to mix with the new charge and at D the 
manner by which the new charge sweeps by the ignition 
device, keeping it cool and avoiding possibilities of pre- 
ignition by undue heating of the terminals of the sparking 
flevice. Thus, by enveloping the sparking device with 
the pure mixture, ignition spreads through the charge with 
its greatest possible velocity, a most desirable condition 
in high-speed motors with side-valve chambers and igni- 
ters within the valve chamber. 



46 



Aviation Engines 





Exhaust. 



Practical condition. 




New charge. 



Fig. 10. — Diagrams Contrasting Action of Two- and Four-Cycle Cylinders 
on Exhaust and Intake Stroke, 



Internal Combustion Engine Theory 47 



THEORY OF THE GAS AXD GASOLINE EXGIITE 

The laws controlling the elements that create a power 
by their expansion by heat due to combustion, when prop- 
erly understood, become a matter of computation in 
regard to their value as an agent for generating power 
in the various kinds of explosive engines. The method 
of heating the elements of power in explosive engines 
greatly widens the limits of temperature as available in 
other types of heat-engines. It disposes of many of the 
practical troubles of hot-air, and even of steam-engines, 
in the simplicity and directness of application of the ele- 
ments of power. In the explosive engine the difficulty 
of conveying heat for producing expansive effect by con- 
vection is displaced by the generation of the required heat 
within the expansive element and at the instant of its 
useful work. The low conductivity of heat to and from 
air has been the great obstacle in the practical develop- 
ment of the hot-air engine; while, on the contrary, it has 
become the source of economy and practicability in the 
development of the internal-combustion engine. 

The action of air, gas, and the vapors of gasoline and 
petroleum oil, whether singly or mixed, is affected by 
changes of temperature practically in nearly the same 
ratio ; but when the elements that produce combustion are 
interchanged in confined spaces, there is a marked differ- 
ence of effect. The oxygen of the air, the hydrogen and 
carbon of a gas, or vapor of gasoline or petroleum oil are 
the elements that by combustion produce heat to expand 
the nitrogen of the air and the watery vapor produced 
by the union of the oxygen in the air and the hydrogen in 
the gas, as well as also the monoxide and carbonic-acid 
gas that may be formed by the union of the carbon of 
gas or vapor with part of the oxygen of the air. The 
various mixtures as between air and gas, or air and vapor, 
with the proportion of the products of combustion left 
in the cylinder from a previous combustion, form the 
elements to be considered in estimating the amount of 



48 Aviation Engines 

pressure that may be obtained by their combustion and 
expansive force. 

EARLY GAS ENGINE FORMS 

The working process of the explosive motor may be 
divided into three principal types : 1. Motors with charges 
igniting at constant volume without compression, such as 
the Lenoir, Hugon, and other similar types now abandoned 
as wasteful in fuel and effect. 2. Motors with charges 
igniting at constant pressure with compression, in which 
a receiver is charged by a pump and the gases burned 
while being admitted to the motor cylinder, such as types 
of the Simon and Brayton engine. 3. Motors with charges 
igniting at constant volume with variable compression, 
such as the later two- and four-cycle motors with compres- 
sion of the indrawn charge; limited in the two-cycle type 
and variable in the four-cycle type with the ratios of the 
clearance space in the cylinder. This principle produces 
the explosive motor of greatest efficiency. 

The phenomena of the brilliant light and its accom- 
panying heat at the moment of explosion .have been wit- 
nessed in the experiments of Dugald Clerk in England, 
the illumination lasting throughout the stroke; but in 
regard to time in a four-cycle engine, the incandescent 
state exists only one-quarter of the running time. Thus 
the time interval, together with the non-conductibility of 
the gases, makes the phenomena of a high-temperature 
combustion within the comparatively cool walls of a cyl- 
inder a practical possibility. 

THE ISOTHERMAL LAW 

The natural laws, long since promulgated by Boyle, 
Gay Lussac, and others, on the subject of the expansion 
and compression of gases by force and by heat, and their 
variable pressures and temperatures when confined, are 
conceded to be practically true and applicable to all gases, 
whether single, mixed, or combined. 



Isothermal Law 49 

The law formulated by Boyle only relates to the com- 
pression and expansion of gases without a change of 
temperature, and is stated in these words: 

// the temperature of a gas he kept constant, its pres- 
sure or elastic force will vary inversely as the volume 
it occupies. 

It is expressed in the formula PXV=C, or pressure 

C C 

X volume = constant. Hence, — =='V and — = P. 

P V 

Thus the curve formed by increments of pressure dur- 
ing the expansion or compression of a given volume of 
gas without change of temperature is designated as the 
isothermal curve in which the volume multiplied by the 
pressure is a constant value in expansion, and inversely 
the pressure divided by the volume is a constant value 
in compressing a gas. 

But as compression and expansion of gases require 
force for their accomplishment mechanically, or by the 
application or abstraction of heat chemically, or by con- 
vection, a second condition becomes involved, which was 
formulated into a law of thermodynamics by Gay Lussac 
under the following conditions: A given volume of gas 
under a free piston expands by heat and contracts by the 
loss of heat, its volume causing a proportional movement 
of a free piston equal to %73 part of the cylinder volume 
for each degree Centigrade difference in temperature, or 
%92 part of its volume for each degree Fahrenheit. With 
a fixed piston (constant volume), the pressure is increased 
or decreased by an increase or decrease of heat in the 
same proportion of % 7 3 part of its pressure for each 
degree Centigrade, or %92 part of its pressure for each 
degree Fahrenheit change in temperature. This is the 
natural sequence of the law of mechanical equivalent, 
which is a necessary deduction from the principle that 



50 Aviation Engines 

nothing in nature can be lost or wasted, for all the heat 
that is imparted to or abstracted from a gaseous body 
must be accounted for, either as heat or its equivalent 
transformed into some other form of energy. In the case 
of a piston moving in a cylinder by the expansive force 
of heat in a gaseous body, all the heat expended in ex- 
pansion of the gas is turned into work; the balance must 
be accounted for in absorption by the cylinder or radiation. 

THE ADIABATIC LAW 

This theory is equally applicable to the cooling of gases 
by abstraction of heat or by cooling due to expansion by 
the motion of a piston. The denominators of these heat 
fractions of expansion or contraction represent the ab- 
solute zero of cold below the freezing-point of water, and 
read — 273° C. or — 492.66° = —460.66° F. below zero; 
and these are the starting-points of reference in com- 
puting the heat expansion in gas-engines. According to 
Boyle's law, called the first law of gases, there are but 
two characteristics of a gas and their variations to be 
considered, viz., volume and pressure: while by the law 
of Gay Lussac, called the second law of gases, a third 
is added, consisting of the value of the absolute tem- 
perature, counting from absolute zero to the temperatures 
at which the operations take place. This is the Adiabatic 
law. 

The ratio of the variation of the three conditions — 
volume, pressure, and heat — from the absolute zero tem- 
perature has a certain rate, in which the volume multi 7 
plied by the pressure and the product divided by the 
absolute temperature equals the ratio of expansion for 
each degree. If a volume of air is contained in a cylinder 
having a piston and fitted with an indicator, the piston, 
if moved to and fro slowly, will alternately compress and 
expand the air, and the indicator pencil will trace a line 
or lines upon the card, which lines register the change 
of pressure and volume occurring in the cylinder. If the 
piston is perfectly free from leakage, and it be supposed 



Adiabatic Law 



51 



that the temperature of the air is kept quite constant, 
then the line so traced is called an Isothermal line, and 
the pressure at any point when multiplied by the volume 
is a constant, according to- Boyle's law, 



pv 



a constant. 



If, however, the piston is moved very rapidly, the air will 
not remain at constant temperature, but the temperature 
will increase because work has been done upon the air, 









13 20' 


C 




























































































































































\ 






























































































1 






















































\ 


\ 




\ 2 


■7 J 


c 




























\ 




\ 














1 




















v 


Na 


































\ 


fk| s 


?'.. 


































\*i 




? 


u 


0.5 


C 
































w . 
































































































































































1 

















ATMOSPHERIC 
LINES 



10 20 



30 



40 50 

VOLUME 



60 70 



80 



90 100 



Fig. 11. — Diagram Isothermal and Adiabatic Lines. 



and the heat has no time to escape by conduction. If no 
heat whatever is lost by any cause, the line will be traced 
over and over again by the indicator pencil, the cooling 
by expansion doing work precisely equalling the heating 
by compression. This is the line of no transmission of 
heat, therefore known as Adiabatic. 

The expansion of a gas % 7 3 of its volume for every 
degree Centigrade, added to its temperature, is equal to 
the decimal .00366, the coefficient of expansion for Centi- 
grade units. To any given volume of a gas, its expansion 
may be computed by multiplying the coefficient by the 



52 Aviation Engines 

number of degrees, and by reversing the process the degree 
of acquired heat may be obtained approximately. These 
methods are not strictly in conformity with the absolute 
mathematical formula, because there is a small increase 
in the increment of expansion of a dry gas, and there is 
also a slight difference in the increment of expansion due 
to moisture in the atmosphere and to the vapor of water 
formed by the union of the hydrogen and oxygen in the 
combustion chamber of explosive engines. 

TEMPERATURE COMPUTATIONS 

The ratio of expansion on the Fahrenheit scale is de- 
rived from the absolute temperature below the freezing- 
point of water (32°) to correspond with the Centigrade 

1 

scale ; therefore = .0020297, the ratio of expansion 

492.66 

from 32° for each degree rise in temperature on the Fah- 
renheit scale. As an example, if the temperature of any 
volume of air or gas at constant volume is raised, say 
from 60° to 2000° F., the increase in temperature will be 

1 

1940°. The ratio will be = .0019206. Then by the 

520.66 

formula : 

Eatio X acquired temp. X initial pressure = the gauge 
pressure; and .0019206 X 1940° X 14.7 = 54.77 lbs. 

By another formula, a convenient ratio is obtained by 

absolute pressure 14.7 

or = .028233 ; then, using the dif- 

absolute temp. 520.66 

ference of temperature as before, .028233 X 1940° = 54.77 
lbs. pressure. 

i$y another formula, leaving out a small increment due 
to specific heat at high temperatures : 



Temperature Computations 53 

Atmospheric pressure X absolute temp. 
T + acquired temp. 

Absolute temp. + initial temp. 

absolute pressure due to the acquired temperature, from 
which the atmospheric pressure is deducted for the 
gauge pressure. Using the foregoing example, we have 
14.7 X 460.66° + 2000° 

= 69.47 — 14.7 = 54.77, the gauge 

460.66 + 60° 

pressure, 460.66 being the absolute temperature for zero 
Fahrenheit. 

For obtaining the volume of expansion of a gas from 
a given increment of heat, we have the approximate 
formula : 

Volume X absolute temp. + acquired temp. 

II. = heated 

Absolute temp. + initial temp. 

volume. In applying this formula to the foregoing ex- 
ample, the figures become: 

460.66° + 2000° 

I. X = 4.72604 volumes. 

460.66 + 60° ■ 

From this last term the gauge pressure may be obtained 
as follows : 

III. 4.72604 X 14.7 = 69.47 lbs. absolute — 14.7 lbs. at- 
mospheric pressure = 54.77 lbs. gauge pressure ; which is 
the theoretical pressure due to heating air in a confined 
space, or at constant volume from 60° to 2000° F. 

By inversion of the heat formula for absolute pressure 
we have the formula for the acquired heat, derived from 
combustion at constant volume from atmospheric pressure 
to gauge pressure plus atmospheric pressure as derived 
from Example I., by which the expression 

absolute pressure X absolute temp, -f initial temp. 

initial absolute pressure 



54 Aviation Engines 

= absolute temperature + temperature of combustion, 
from which the acquired temperature is obtained by sub- 
tracting the absolute temperature. 

69.47 X 460.66 + 60 

Then, for example, = 2460.66, and 

14.7 

2460.66 — 460.66 = 2000°, the theoretical heat of combus- 
tion. The dropping of terminal decimals makes a small 
decimal difference in the result in the different formulas. 



HEAT AND ITS WORK 

By Joule's law of the mechanical equivalent of heat, 
whenever heat is imparted to an elastic body, as air or 
gas, energy is generated and mechanical work produced 
by the expansion of the air or gas. When the heat is im- 
parted by combustion within a cylinder containing a mov- 
able piston, the mechanical work becomes an amount 
measurable by the observed pressure and movement of 
the piston. The heat generated by the explosive elements 
and the expansion of the non-combining elements of nitro- 
gen and water vapor that may have been injected into the 
cylinder as moisture in the air, and the water vapor 
formed by the union of the oxygen of the air with the 
hydrogen of the gas, all add to the energy of the work 
from their expansion by the heat of internal combustion. 
As against this, the absorption of heat by the walls of the 
cylinder, the piston, and cylinder-head or clearance walls, 
becomes a modifying condition in the force imparted to 
the moving piston. 

It is found that when any explosive mixture of air and 
gas or hydrocarbon vapor is fired, the pressure falls far 
short of the pressure computed from the theoretical effect 
of the heat produced, and from gauging the expansion of 
the contents of a cylinder. It is now well known that in 
practice the high efficiency which is promised by theoret- 
ical calculation is never realized; but it must always be 



Heat and Its Work 55 

remembered that the heat of combustion is the real agent, 
and that the gases and vapors are but the medium for the 
conversion of inert elements -of power into the activity of 
energy by their chemical union. The theory of combustion 
has been the leading stimulus to large expectations with 
inventors and constructors of explosive motors; its en- 
tanglement with the modifying elements in practice has 
delayed the best development in construction, and as yet 
no really positive design of best form or action seems to 
have been accomplished, although great progress has been 
made during the past decade in the development of speed, 
reliability, economy, and power output of the individual 
units of this comparatively new power. 

One of the most serious difficulties in the practical de- 
velopment of pressure, due to the theoretical computations 
of the pressure value of the full heat, is probably caused 
by imparting the heat of the fresh charge to the balance 
of the previous charge that has been cooled by expansion 
from the maximum pressure to near the atmospheric 
pressure of the exhaust. The retardation in the velocity 
of combustion of perfectly mixed elements is now well 
known from experimental trials with measured quantities ; 
-but the principal difficulty in applying these conditions 
to the practical work of an explosive engine where a ne- 
cessity for a large clearance space cannot be obviated, 
is in the inability to obtain a maximum effect from the 
imperfect mixture and the mingling of the products of 
the last explosion with the new mixture, which produces 
a clouded condition that makes the ignition of the mass 
irregular or chattering, as observed in the expansion lines 
of indicator cards; but this must not be confounded with 
the reaction of the spring in the indicator. 

Stratification of the mixture has been claimed as taking 
place in the clearance chamber of the cylinder; but this 
is not a satisfactory explanation in view of the vortical 
effect of the violent injection of the air and gas or vapor 
mixture. It certainly cannot become a perfect mixture 
in the time of a stroke of a high-speed motor of the two- 



56 



Aviation Engines 



cycle class. In a four-cycle engine, making 1,500 revolu- 
tions per minute, the injection and compression in any 
one cylinder take place in one twenty-fifth of a second — 
formerly considered far too short a time for a perfect 
infusion of the elements of combustion but now very easily 
taken care of despite the extremely high speed of numer- 
ous aviation and automobile power-plants. 



Table I. — Explosion at Constant Volume in a Closed Chamber. 



Dia- 




Temp, of 

Injection 

Fahr. 


Time 


Observed 


Com- 


gram 
Curve 


Mixture Injected. 


of Explo- 
sion. 


Gauge 
Pressure. 


puted 
Temp. 


Fig. 8. 




Second. 


Pounds. 


Fahr. 


a 


1 volume gas to 14 volumes air. 


64° 


0.45 


40. 


1,483° 


b 


1 " " " 13 


51° 


0.31 


51.5 


1,859° 


c 


1 " " " 12 


51° 


0.24 


60. 


2,195° 


d 


1 " " " 11 


51° 


0.17 


61. 


2,228° 


e 


1 " " " 9 


62° 


0.08 


78. 


2,835° 


f 


1 " " " 7 


62° 


0.06 


87. 


3,151° 


9 


1 " " " 6 


51° 


0.04 


90. 


3,257° 


h 


1 " " " 5 " 


51° 


0.055 


91. 


3,293° 


% 


-^ K U U 4 U U 


66° 


0.16 


80. 

■ 


2,871° 



In an examination of the times of explosion and the 
corresponding pressures in both tables, it will be seen that 
a mixture of 1 part gas to 6 parts air is the most effective 
and will give the highest mean pressure in a gas-engine. 
There is a limit to the relative proportions of illuminating 
gas and air mixture that is explosive, somewhat variable, 
depending upon the proportion of hydrogen in the gas. 
With ordinary coal-gas, 1 of gas to 15 parts of air; and 
on the lower end of the scale, 1 volume of gas to 2 parts 
air, are non-explosive. With gasoline vapor the explosive 
effect ceases at 1 to 16, and a saturated mixture of equal 
volumes of vapor and air will not explode, while the most 
intense explosive effect is from a mixture of 1 part vapor 
to 9 parts air. In the use of gasoline and air mixtures 
from a carburetor, the best effect is from 1 part Saturated 
air to 8 parts free air. 



Heat and Its Work 



57 



Table II. — Properties and Explosive Temperature of a Mixture op 
One Part of Illuminating Gas of 660 Thermal Units per Cubic Foot 
with Various Proportions of Air without Mixture of Charge with 
the Products of a Previous Explosion. 



0? 

a 

* J 

.2 >> 


'2 . 
OS 

S.H 

OS 

■s-s 
!§ 


Specific Heat. 

Heat Units Required 

to Raise 1 Lb. 1 Deg. 

Fahrenheit. 


Heat to 
Raise One 

Cubic 

: Foot of 

Mixture 

1 Deg. 

Fahr. 


>> 

- . 

o.2 

w| 

P 

-4-> 

Bj 
O 
W 


Ratio 
Col. 


03 k! 

1. 

1 


« X o 
m -3 do 

S-5g 


O 

a 

1 


Constant 
Pressure. 


Constant 
Volume. 


— 20 
|3 


6 to 1 . . 

7 to 1 . . 

8 to 1 . . 

9 to 1 . . 

10 to 1 . . 

11 to 1. . 

12 to 1 . . 


. .074195 
. .075012 
. .075647 
. .076155 
. .076571 
. .076917 
. .077211 


.2668 
.2628 
.2598 
.2575 
.2555 
.2540 
.2526 


.1913 
.1882 
.1858 
.1846 
.1825 
.1813 
.1803 


.014189 
.014116 
.014059 
.014013 
.013976 
.013945 
.013922 


94.28 

82. 

73.33 

66. 

60. 

55. 

50.77 


6644.6 

5844.4 

5216.1 

4709.9 

4293. 

3944. 

3646.7 


.465 

.518 
.543 
.56 
.575 

.585 

.58 


3090 
3027 
2832 
2637 
2468 
2307 
2115 



The weight of a cubic foot of gas and air mixture as 
given in Col. 2 is found by adding the number of volumes 
of air multiplied by its weight, .0807, to one volume of gas 
of weight .035 pound per cubic foot and dividing by the 
total number of volumes; for example, as in the table, 

.5192 
6 X .0807 = = .074195 as in the first line, and so on 



for any mixture or for other gases of different specific 
weight per cubic foot. The heat units evolved by com- 
bustion of the mixture (Col. 6) are obtained by dividing 
the total heat units in a cubic foot of gas by the total 



660 



proportion of the mixture, 



94.28 as in the first line 



of the table. Col. 5 is obtained by multiplying the weight 
of a cubic foot of the mixture in Col. 2 by the specific heat 

Col. 6 

at a constant volume (Col. 4), = Col. 7 the total heat 

Col. 5 



58 Aviation Engines 

ratio, of which Col. 8 gives the usual combustion efficiency 
— Col. 7 X Col. 8 gives the absolute rise in temperature 
of a pure mixture, as given in Col. 9. 

The many recorded experiments made to solve the dis- 
crepancy between the theoretical and the actual heat de- 
velopment and resulting pressures in the cylinder of an 
explosive motor, to which much discussion has been given 
as to the possibilities of dissociation and the increased 
specific heat of the elements of combustion and non-com- 
bustion, as well, also, of absorption and radiation of heat, 
have as yet furnished no satisfactory conclusion as to 
what really takes place within the cylinder walls. There 
seems to be very little known about dissociation, and 
somewhat vague theories have been advanced to explain 
the phenomenon. The fact is, nevertheless, apparent as 
shown in the production of water and other producer 
gases by the use of steam in contact with highly incan- 
descent fuel. It is known that a maximum explosive 
mixture of pure gases, as hydrogen and oxygen or car- 
bonic oxide and oxygen, sutlers a contraction of one-third 
their volume by combustion to their compounds, steam or 
carbonic acid. In the explosive mixtures in the cylinder 
of a motor, however, the combining elements form so 
small a proportion of the contents of the cylinder that 
the shrinkage of their volume amounts to no more than 
3 per cent, of the cylinder volume. This by no means 
accounts for the great heat and pressure differences be- 
tween the theoretical and actual effects. 

CONVERSION OF HEAT TO POWER 

The utilization of heat in any heat-engine has long 
been a theme of inquiry and experiment with scientists 
and engineers, for the purpose of obtaining the best prac- 
tical conditions and construction of heat-engines that would 
represent the highest efficiency or the nearest approach 
to the theoretical value of heat, as measured by empirical 
laws that have been derived from experimental researches 
relating to its ultimate volume. It is well known that the 



Requisites for Best Power Effect 59 

steam-engine returns only from 12 to 18 per cent, of the 
power due to the heat generated by the fuel, about 25 
per cent, of the total heat being lost in the chimney, the 
only use of which is to create a draught for the fire; the 
balance, some 60 per cent., is lost in the exhaust and by 
radiation. The problem of utmost utilization of force 
in steam has nearly reached its limit. 

The internal-combustion system of creating power is 
comparatively new in practice, and is but just settling 
into definite shape by repeated trials and modification of 
details, so as to give somewhat reliable data as to what 
may be expected from the rival of the steam-engine as 
a prime mover. For small powers, the gas, gasoline, and 
petroleum-oil engines are forging ahead at a rapid rate, 
filling the thousand wants of manufacture and business 
for a power that does not require expensive care, that 
is perfectly safe at all times, that can be used in any place 
in the wide world to 'which its concentrated fuel can be 
conveyed, and that has eliminated the constant handling 
of crude fuel and water. 

REQUISITES FOR BEST POWER EFFECT 

The utilization of heat in a gas-engine is mainly due 
to the manner in which the products entering into com- 
bustion are distributed in relation to the movement of 
the piston. The investigation of the foremost exponent 
of the theory of the explosive motor was prophetic in 
consideration of the later realization of the best condi- 
tions under which these motors can be made to meet the 
requirements of economy and practicability. As early as 
1862, Beau de Rocha announced, in regard to the coming 
power, that four requisites were the basis of operation 
for economy and best effect. 1. The greatest possible 
cylinder volume with the least possible cooling surface. 
2. The greatest possible rapidity of expansion. Hence, 
high speed. 3. The greatest possible expansion. Long 
stroke. 4. The greatest possible pressure at the com- 
mencement of expansion. High compression. 



CHAPTER III 

Efficiency of Internal Combustion Engines — Various Measures of Effi- 
ciency — Temperatures and Pressures — Factors Governing Economy 
— Losses in Wall Cooling — Value of Indicator Cards — Compres- 
sion in Explosive Motors — Factors Limiting Compression — Causes 
of Heat Losses and Inefficiency — Heat Losses to Cooling Water. 

EFFICIENCY OF INTERNAL COMBUSTION ENGINES 

Efficiencies are worked out through intricate formulas 
for a variety of theoretical and unknown conditions of 
combustion in the cylinder: ratios of clearance and cyl- 
inder volume, and the uncertain condition of the products 
of combustion left from the last impulse and the wall 
temperature. But they are of but little value, except as 
a mathematical inquiry as to possibilities. The real com- 
mercial efficiency of a gas or gasoline-engine depends upon 
the volume of gas or liquid at some assigned cost, re- 
quired per actual brake horse-power per hour, in which 
an indicator card should show that the mechanical action 
of the valve gear and ignition was as perfect as practi- 
cable, and that the ratio of clearance, space, and cylinder 
volume gave a satisfactory terminal pressure and com- 
pression: i.e., the difference between the power figured 
from the indicator card and the brake power being the 
friction loss of the engine. 

In four-cycle motors of the compression type, the effi- 
ciencies are greatly advanced by compression, producing 
a more complete infusion of the mixture of gas or vapor 
and air, quicker firing, and far greater pressure than is 
possible with the two-cycle type previously described. In 
the practical operation of the gas-engine during the past 
twenty years, the gas-consumption efficiencies per indi- 
cated horse-power have gradually risen from 17 per cent. 
to a maximum of 40 per cent, of the theoretical heat, and 

60 



Various Measures of Efficiency 61 

this has been done chiefly through a decreased combustion 
chamber and increased compression — the compression hav- 
ing gradually increased in practice from 30 lbs. per square 
inch to above 100; but there seems to be a limit to com- 
pression, as the efficiency ratio decreases with greater in- 
crease in compression. It has been-shown that an ideal 
efficiency of 33 per cent, for 38 lbs. compression vail in- 
crease to 40 per cent, for 66 lbs., and 43 per cent, for 88 
lbs. compression. On the other hand, greater compression 
means greater explosive pressure and greater strain on 
the engine structure, which will probably retain in future 
practice the compression between the limits of 40 and 90 
lbs. except in super-compression engines intended for 
high altitude work where compression pressures as high 
as 125 pounds have been used. 

In .experiments made by Dugald Clerk, in England, 
with a combustion chamber equal to 0.6 of the space swept 
by the piston, with a compression of 38 lbs., the consump- 
tion of gas was 24 cubic feet per indicated horse-power 
per hour. With 0.4 compression space and 61 lbs. com- 
pression, the consumption of gas was 20 cubic feet per 
indicated horse-power per hour; and with 0.34 compres- 
sion space and 87 lbs. compression, the consumption of 
gas fell to 14.8 cubic feet per indicated horse-power per 
hour — the actual efficiencies being respectively 17, 21, and 
25 per cent. This was with a Crossley four-cycle engine. 

VARIOUS MEASURES OF EFFICIENCY 

The efficiencies in regard to power in a heat-engine 
may be divided into four kinds, as follows: I. The first 
is known as the maximum theoretical efficiency of a per- 
fect engine (represented by the lines in the indicator dia- 

T.-To 

gram). It is expressed bv the formula and shows 

T, 

the work of a perfect cycle in an engine working between 
the received temperature+ absolute temperature (TJ and 



62 Aviation Engines 

the initial atmospheric temperature •+ absolute tempera- 
ture (T ). II. The second is the actual heat efficiency, 
or the ratio of the heat turned into work to the total heat 
received by the engine. It expresses the indicated horse- 
power. III. The third is the ratio between the second 
or actual heat efficiency and the first or maximum theo- 
retical efficiency of a perfect cycle. It represents the 
greatest possible utilization of the power of heat in an 
internal-combustion engine. IV. The fourth is the me- 



5% Engine 
Friction 



100 °/o 
Supplied 




40%o Lost to 

Cooling Water 



$4°/o Rejected in Exhaust and Radiation 



Fig. 12. — Graphic Diagram Showing Approximate Utilization of Fuel 
Burned in Internal-Combustion Engine, 

chanical efficiency. This is the ratio between the actual 
horse-power delivered by the engine through a dyna- 
mometer or measured by a brake (brake horse-power), 
and the indicated horse-power. The difference between 
the two is the power lost by engine friction. In regard 
to the general heat efficiency of the materials of power 
in explosive engines, we find that with good illuminating 
gas the practical efficiency varies from 25 to 40 per cent. ; 
kerosene-motors, 20 to 30 ; gasoline-motors, 20 to 32 ; acet- 
ylene, 25 to 35 ; alcohol, 20 to 30 per cent, of their heat 
value. The great variation is no doubt due to imperfect 
mixtures and variable conditions of the old and new charge 
in the cylinder ; uncertainty as to leakage and the perf ec- 



Temperatures and Pressures 63 

tion of combustion. In the Diesel motors operating under 
high pressure, up to nearly 500 pounds, an efficiency of 
36 per cent, is claimed. 

The graphic diagram at Fig. 12 is of special value as 
it shows clearly how the heat produced by charge combus- 
tion is expended in an engine of average design. 

On general principles the greater difference between 
the heat of combustion and the heat at exhaust is the 
relative measure of the heat turned into work, which 
represents the degree of efficiency without loss during 
expansion. The mathematical formulas appertaining to 
the computation of the element of heat and its work in 
an explosive engine are in a large measure dependent 
upon assumed values, as the conditions of the heat of 
combustion are made uncertain by the mixing of the fresh 
charge with the products of a previous combustion, and 
by absorption, radiation, and leakage. The computation 
of the temperature from the observed pressure may be 
made as before explained, but for compression-engines 
the needed starting-points for computation are very un- 
certain, and can only be approximated from the exact 
measure and value of the elements of combustion in a 
cylinder charge. 

TEMPERATURES ASTD PRESSURES 

Owing to the decrease from atmospheric pressure in 
the indrawing charge of the cylinder, caused by valve and 
frictional obstruction, the compression seldom starts above 
13 lbs. absolute, especially in high-speed engines. Col. 3 
in the following table represents the approximate absolute 
compression pressure for the clearance percentage and 
ratio in Cols. 1 and 2, while Col. 4 indicates the gauge 
pressure from the atmospheric line. The temperatures in 
Col. 5 are due to the compression in Col. 3 from an as- 
sumed temperature of 560° F. in the mixture of the fresh 
charge of 6 air to 1 gas with the products of combustion 
left in the clearance chamber from the exhaust stroke of 
a medium-speed motor. This temperature is subject to 



64 



Aviation Engines 



considerable variation from the difference in the heat- 
unit power of the gases and vapors used for explosive 
power, as also of the cylinder-cooling effect. In Col. 6 is 
given the approximate temperatures of explosion for a 
mixture of air 6 to gas 1 of 660 heat units per cubic foot, 
for the relative values of the clearance ratio in Col. 2 at 
constant volume. 



Table III. — Gas-Engine Clearance Ratios, Approximate Compression, 
Temperatures of Explosion and Explosive Pressures with a Mix- 
ture of Gas of 660 Heat Units per Cubic Foot and Mixture of Gas 
1 to 6 of Air. 



*o 




11 




og.S 


o H 


a 
o 




t* 




















1 

Jl 


> 


3 

a 

St 

1* 




si 


5 E-"S 

m o « 

ft fi £ 


BAA 

hi «* 
ft a 


S a* 

ft-2 

M O 


C 0) 


h 


si 

1- 

c o 






III 

■a o 

OfiM 


1* 

g.So 
O 


Dtotl 

5ft 


* fl u 

S ^-2:3 
3 -3 ft if 




ft a 
O 3 

O 


|°1 


J3-23 


!*S 






^ o * 


>> O x S 

J JgW ft 


1£ 




h a «« 


o 




< 




<! 


«! 


«! 




<J 


1 


2 


3 


4 


5 


6 


7 


8 


9' 






Lbs. 




Deg. 


Deg. 


.Lbs. 


Lbs. 


Deg. 


.50 


3. 


57. 


42. 


822 


2488 


169 


144 


2027 


.444 


3.25 


65. 


50. 


846 


2568 


197 


182 


2107 


.40 


3.50 


70. 


55. 


868 


2638 


212 


197 


2177 


.363 


3.75 


77. 


62. 


889 


2701 


234 


219 


2240 


.333 


4. 


84. 


69. 


910 


2751 


254 


239 


2290 


.285 


4.50 


102. 


88. 


955 


2842 


303 


288 


2381 


.25 


5. 




114. 


99. 


983 


2901 


336 


321 


2440 



FACTORS GOVERNING ECONOMY 

In view of the experiments in this direction, it clearly 
shows that in practical work, to obtain the greatest econ- 
omy per effective brake horse-power, it is necessary: 1st. 
To transform the heat into work with the greatest rapid- 
ity mechanically allowable. This means high piston speed. 
2d. To have high initial compression. 3d. To reduce the 
duration of contact between the hot gases and the cylinder 
walls to the smallest amount possible; which means short 
stroke and quick speed, with a spherical cylinder head. 
4th. To adjust the temperature of the jacket water to 



Losses in Wall Cooling 65, 

obtain the most economical output of actual power. This 
means water-tanks or water-coils, with air-cooling surfaces 
suitable and adjustable to the most economical requirement 
of the engine, which by late trials requires the jacket water 
to be discharged at about 200° F. 5th. To reduce the 
wall surface of the clearance space or combustion chamber 
to the smallest possible area, in proportion to its required 
volume. This lessens the loss of the heat of combustion by 
exposure to a large surface, and allows of a higher mean 
wall temperature to facilitate the heat of compression. 

LOSSES IN WALL COOLING 

In an experimental investigation of the efficiency of a 
gas-engine under variable piston speeds made in France, 
it was found that the useful effect increases with the ve- 
locity of the piston — that is, with the rate of expansion 
of the burning gases with mixtures of uniform volumes; 
so that the variations of time of complete combustion 
at constant pressure, and the variations due to speed, in 
a way compensate in their efficiencies. The dilute mix- 
ture, being slow burning, will have its time and pressure 
quickened by increasing the speed. 

Careful trials give unmistakable evidence that the use- 
ful effect increases with the velocity of the piston — that 
is, with the rate of expansion of the burning gases. The 
time necessary for the explosion to become complete and 
to attain its maximum pressure depends not only on the 
composition of the mixture, but also upon the rate of ex- 
pansion. This has been verified in experiments with a 
high-speed motor, at speeds from 500 to 2,000 revolutions 
per minute, or piston speeds of from 16 to 64 feet per 
second. The increased speed of combustion due to in- 
creased piston speed is a matter of great importance to 
builders of gas-engines, as well as to the users, as indi- 
cating the mechanical direction of improvements to lessen 
the wearing strain due to high speed and to lighten the 
vibrating parts with increased strength, in order that the 



66 Aviation Engines 

balancing of high-speed engines may be accomplished with 
the least weight. 

From many experiments made in Europe and in the 
United States, it has been conclusively proved that ex- 
cessive cylinder cooling by the water-jacket results in a 
marked loss of efficiency. In a series of experiments with 
a simplex engine in France, it was found that a saving 
of 7 per cent, in gas consumption per brake horse-power 
was made by raising the temperature of the jacket water 
from 141° to 165° F. A still greater saving was made in 
a trial with an Otto engine by raising the temperature of 
the jacket water from 61° to 140° F. — it being 9.5 per 
cent, less gas per brake horse-power. 

It has been stated that volumes of similar cylinders 
increase as the cube of their diameters, while the surface 
of their cold walls varies as the square of their diameters ; 
so that for large cylinders the ratio of surface to volume 
is less than for small ones. This points to greater econ- 
omy in the larger engines. The study of many experi- 
ments goes to prove that combustion takes place gradually 
in the gas-engine cylinder, and that the rate of increase 
of pressure or rapidity of firing is controlled by dilution 
and compression of the mixture, as well as by the rate 
of expansion or piston speed. The rate of combustion 
also depends on the size and shape of the explosion cham- 
ber, and is increased by the mechanical agitation of the 
mixture during combustion, and still more by the mode 
of firing. 

VALUE OF INDICATOR CARDS 

To the uninitiated, indicator cards are considerable 
of a mystery; to those capable of reading them they form 
an index relative to the action of any engine. An indi- 
cator card, such as shown at Fig. 13, is merely a graphical 
representation of the various pressures existing in the 
cylinder for different positions of the piston. The length 
is to some scale that represents the stroke of the piston. 
During the intake stroke, the pressure falls below the 



Value of Indicator Cards 



67 



atmospheric line. During compression, the curve gradu- 
ally becomes higher owing to increasing pressure as the 
volume is reduced. After ignition the pressure line moves 



F Max™ Press. 

& Temp. 



Actual Indicator 

J)iagram from 

Otto Engine. 




j<— — TMslength is proporUonaUafh^siroke of Engine.— 
Fig. 13. — Otto Four-Cycle Card. 

upward almost straight, then as the piston goes down on 
the explosion stroke, the pressure falls gradually to the 
point of exhaust valve, opening when the sudden release 
di the imprisoned gas causes a reduction in pressure to 
nearly atmospheric. An indicator card, or a series of 




Fig. 14-. — Diesel Motor Card. 



them, will always show by its lines the normal or defective 
condition of the inlet valve and passages; the actual line 
of compression; the firing moment; the pressure of ex- 
plosion; the velocity of combustion; the normal or defec- 
tive line of expansion, as measured by the adiabatic curve, 



68 Aviation Engines 

and the normal or defective operation of the exhaust 
valve, exhaust passages, and exhaust pipe. In fact, all 
the cycles of an explosive motor may be made a practical 
study from a close investigation of the lines of an indi- 
cator card. 

A most unique card is that of the Diesel motor (Fig. 
14), which involves a distinct principle in the design and 
operation of internal-combustion motors, in that instead 
of taking a mixed charge for instantaneous explosion, its 
charge primarily is of air and its compression to a press- 
ure at which a temperature is attained above the igniting 
point of the fuel, then injecting the fuel under a still 
higher pressure by which spontaneous combustion takes 
place gradually with increasing volume over the compres- 
sion for part of the stroke or until the fuel charge is con- 
sumed. The motor thus operating between the pressures 
of 500 and 35 lbs. per square inch, with a clearance of 
about 7 per cent., has given an efficiency of 36 per cent. 
of the total heat value of kerosene oil. 

COMPRESSION IN EXPLOSIVE MOTORS 

That the compression in a gas, gasoline, or oil-engine 
has a direct relation to the power obtained, has been long 
known to experienced builders, having been suggested by 
M. Beau de Eocha, in 1862, and afterward brought into 
practical use in the four-cycle or Otto type about 1880. 
The degree of compression has had a growth from zero, 
in the early engines, to the highest available due to the 
varying ignition temperatures of the different gases and 
vapors used for explosive fuel, in order to avoid prema- 
ture explosion from the heat of compression. Much of 
the increased power for equal-cylinder capacity is due to 
compression of the charge from the fact that the most 
powerful explosion of gases, or of any form of explosive 
material, takes place when the particles are in the closest 
contact or cohesion with one another, less energy in this 
form being consumed by the ingredients themselves to 
bring about their chemical combination, and consequently 



Value of Compression 



69 



more energy is given out in useful or available work. 
This is best shown by the ignition of gunpowder, which, 
when ignited in the open air,- burns rapidly, but without 
explosion, an explosion only taking place if the powder 
be confined or compressed into a small space. 



2500 
2400 
2300 
2200 
2100 
2000 
1900 
-1800 
1700 
1600 
1500 
1400 
1300 

e 
























""^•Sis. 


















^Sl5_ 


S^ 
















^L^ S 


^//?s 
















' <1Ac 


41* 
















^<L^ 


//? 
















^2^ 


L^? 
















-igjS. j 


















1 <3a~ 


















,ii <S^ : 


^ 








Nl 


























































5 


, ! 


tatio of C< 


)mpressior 
5 ' 


i 

3. 


75 3 


5 3. 


25 ; 




| J J , ' 111 
Piston Stroke Volume 

.20 .222 .25 -.285 .333 .363 .40 .444 .50 



Fig. 15. — Diagram of Heat in the Gas Engine Cylinder. 



In a gas or gasoline-motor with a small clearance or 
compression space — with high compression — the surface 
with which the burning gases come into contact is much 
smaller in comparison with the compression space in a 
low-compression motor. Another advantage of a high- 
compression motor is that on account of the smaller clear- 
ance of combustion space less cooling water is required 
than "with a low-compression motor, as the temperature, 



70 Aviation Engines 

and consequently the pressure, falls more rapidly. The 
loss of heat through the water-jacket is thus less in the 
case of a high-compression than in that of a low-compres- 
sion motor. In the non-compression type of motor the 
best results were obtained with a charge of 16 to 18 parts 
of gas and 100 parts of air, while in the compression type 
the best results are obtained with an explosive mixture 
of 7 to 10 parts of gas and 100 parts of air, thus showing 
that by the utilization of compression a weaker charge 
with a greater thermal efficiency is permissible. 

It has been found that the explosive pressure resulting 
from the ignition of the charge of gas or gasoline-vapor 
and air in the gas-engine cylinder is about 4j4 times the 
pressure prior to ignition. The difficulty about getting 
high compression is that if the pressure is too high the 
charge is likely to ignite prematurely, as compression 
always results in increased temperature. The cylinder 
may become too hot, a deposit of carbon, a projecting 
electrode or plug body in the cylinder may become in- 
candescent and ignite the charge which has been exces- 
sively heated by the high compression and mixture of 
the hot gases of the previous explosion. 

FACTORS LIMITING COMPRESSION 

With gasoline-vapor and air the compression should not 
be raised above about 90 to 95 pounds to the square inch, 
many manufacturers not going above 65 or 70 pounds. 
For natural gas the compression pressure may easily be 
raised to from 85 to 100 pounds per square inch. For 
gases of low calorific value, such as blast-furnace or pro- 
ducer-gas, the compression may be increased to from 140 
to. 190 pounds. In fact the ability to raise the compres- 
sion to a high point with these gases is one of the prin- 
cipal reasons for their successful adoption for gas-engine 
use. In kerosene injection engines the compression of 250 
pounds per square inch has been used with marked econ- 
omy. Many troubles in regard to loss of power and in- 
crease of fuel have occurred and will no doubt continue, 



Factors Limiting Compression 



71 



owing to the wear of valves, piston, and cylinder, which 
produces a loss in compression and explosive pressure 
and a waste of fuel by leakage. Faulty adjustment of 
valve movement is also a cause of loss of power; which 
may be from tardy closing of the inlet-valve or a too early 
opening of the exhaust-valve. 

The explosive pressure varies to a considerable amount 
in proportion to the compression pressure by the differ- 
ence in fuel value and the proportions of air mixtures, 
so that for good illuminating gas the explosive pressure 
may be from 2.5 to 4 times the compression pressure. 
For natural gas 3 to 4.5, for gasoline 3 to 5, for producer- 
gas 2 to 3, and for kerosene by injection 3 to 6. 

The compression temperatures, although well known 
and easily computed from a known normal temperature 
of the explosive mixture, are subject to the effect of the 
uncertain temperature of the gases of the previous ex- 
plosion remaining in the cylinder, the temperature of its 
walls, and the relative volume of the charge, whether full 
or scant; which are terms too variable to make any com- 
putations reliable or available. 

For the theoretical compression temperatures from a 
known normal temperature, we append a table of the rise 
in temperature for the compression pressures in the fol- 
lowing table: 

Table IV. — Compression Temperatures from a Normal Temperature of 
60 Degrees Fahrenheit 



100 lbs. gauge 484° 

90 lbs. gauge 459° 

80 lbs. gauge 433° 

70 lbs. gauge 404° 



60 lbs. gauge 373° 

50 lbs. gauge 339° 

40 lbs. gauge 301° 

30 lbs. gauge 258° 



CHART FOR DETERMINING COMPRESSION PRESSURES 

A very useful chart (Fig. 16) for determining com- 
pression pressures in gasoline-engine cylinders for vari- 
ous ratios of compression space to total cylinder volume 
is given by P. S. Tice, and described in the Chilton Au- 
tomobile Directory by the originator as follows: 



72 



Aviation Engines 



It is many times desirable to have at hand a conve- 
nient means for at once determining with accuracy what 
the compression pressure will be in a gasoline-engine cyl- 
inder, the relationship between the volume of the com- 
pression space and the total cylinder volume or that swept 
by the piston being known. The curve at Fig. 16 is 
offered as such a means. It is based on empirical data 




■I •* 3 * 

COMPRESSION VOLUME EXPRESSED /H E/iACT/OA/S OF TOTAL. CYUNDEX VOLUME. 



Fig. 16. 



-Chart Showing Relation Between Compression Volume 
and Pressure. 



gathered from upward of two dozen modern automobile 
engines and represents what may be taken to be the results 
as found in practice. It is usual for the designer to find 
compression pressure values, knowing the volumes from 
the equation 

----- ■©" •■ > 



which is for adiabatic compression of air. Equation (1) 
is right enough in general form but gives results which 



Determining Compression Pressures 73 

are entirely too high, as almost all designers know from 
experience. The trouble lies in the interchange of heat 
between the compressed gases and the cylinder walls, in 
the diminution of the exponent (1.4 in the above) due to the 
lesser ratio of specific heat of gasoline vapor and in the 
transfer of heat from the gases which are being com- 
pressed to whatever fuel may enter the cylinder in an 
unvaporized condition. Also, there is always some piston 
leakage, and, if the form of the equation (1) is to be 
retained, this also tends to lower the value of the ex- 
ponent. From experience with many engines, it appears 
that compression reaches its highest value in the cylinder 
for but a short range of motor speeds, usually during the 
mid-range. Also, it appears that, at those speeds at which 
compression shows its highest values, the initial pressure 
at the start of the compression stroke is from .5 to .9 lb. 
below atmospheric. Taking this latter loss value, which 
shows more often than those of lesser value, the compres- 
sion is seen to start from an initial pressure of 13.9 lbs. 
per sq. in. absolute. 

Also, experiment shows that if the exponent be given 
the value 1.26, instead of 1.4, the equation will embrace 
all heat losses in the compressed gas, and compensate for 
the changed ratio of specific heats for the mixture and 
also for all piston leakage, in the average engine with 
rings in good condition and tight. In the light of the 
foregoing, and in view of results obtained from its use, 
the above curve is offered — values of P 2 being found 
from the equation 

P 2 = 13.8 g) 

In using this curve it must be remembered that press- 
ures are absolute. Thus: suppose it is desired to know 
the volumetric relationships of the cylinder for a com- 
pression pressure of 75 lbs. gauge. Add atmospheric 
pressure to the desired gauge pressure 14.7 + 75 = 89.7 
lbs. absolute. Locate this pressure on the scale of ordi- 



74 Aviation Engines 

nates and follow horizontally across to the curve and then 
vertically downward to the scale of abscissas, where the 
ratio of the combustion chamber volume to the total cyl- 
inder volume is given, which latter is equal to the sum of 
the combustion chamber volume and that of the piston 
sweep. In the above case it is found that the combustion 
space for a compression pressure of 75 lbs. gauge will be 
.225 of the total cylinder volume, or .225 -=- 775 = .2905 
of the piston sweep volume. Conversely, knowing the 
volumetric ratios, compression pressure can be read di- 
rectly by proceeding from the scale of abscissas verti- 
cally to the curve and thence horizontally to the scale of 
ordinate s. 

CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVE MOTORS 

The difference realized in the practical operation of 
an internal combustion heat engine from the computed 
effect derived from the values of the explosive elements 
is probably the most serious difficulty that engineers have 
encountered in their endeavors to arrive at a rational 
conclusion as to where the losses were located, and the 
ways and means of design that would eliminate the causes 
of loss and raise the efficiency step by step to a reason- 
able percentage of the total efficiency of a perfect cycle. 

An authority on the relative condition of the chemical 
elements under combustion in closed cylinders attributes 
the variation of temperature shown in the fall of the ex- 
pansion curve, and the suppression or retarded evolution 
of heat, entirely to the cooling action of the cylinder walls, 
and to this nearly all the phenomena hitherto obscure in 
the cylinder of a gas-engine. Others attribute the great 
difference between the theoretical temperature of combus- 
tion and the actual temperature realized in the practical 
operation of the gas-engine, a loss of more than one-half 
of the total heat energy of the combustibles, partly to the 
dissociation of the elements of combustion at extremely 
high temperatures and their reassociation by expansion 
in the cylinder, to account for the supposed continued 






Causes of Heat Loss 



75 



combustion and extra adiabatic curve of the expansion 
line on the indicator card. 

The loss of heat to the walls of the cylinder, piston, 
and clearance space, as regards the proportion of wall 
surface to the volume, has gradually brought this point 




Fig. 17. — The Thompson Indicator, an Instrument for Determining Com- 
pressions and Explosion Pressure Values and Recording Them on Chart. 

to its smallest ratio in the concave piston-head and glob- 
ular cylinder-head, with the smallest possible space in the 
inlet and exhaust passage. The wall surface of a cylin- 
drical clearance space or combustion chamber of one-half 
its unit diameter in length is equal to 3.1416 square units, 
its volume but 0.3927 of a cubic unit: while the same wall 



76 



Aviation Engines 



surface in a spherical form has a volume of 0.5236 of a 
cubic unit. It will be readily seen that the volume is in- 
creased 33% per cent, in a spherical over a cylindrical 
form for equal wall surfaces at the moment of explosion, 
when it is desirable that the greatest amount of heat is 
generated, and carrying with it the greatest possible press- 
ure from which the expansion takes place by the movement 
of the piston. 

The spherical form cannot continue during the stroke 
for mechanical reasons; therefore some proportion of 
piston stroke of cylinder volume must be found to cor- 
respond with a spherical form of the combustion chamber 
to produce the least loss of heat through the walls during 




Fig. 18. — Spherical Combustion 
Chamber. 



Fig. 19. — Enlarged Combustion 
Chamber. 



the combustion and expansion part of the stroke. This 
idea is illustrated in Figs. 18 and 19, showing how the 
relative volumes of cylinder stroke and combustion cham- 
ber may be varied to suit the requirements due to the 
quality of the elements of combustion. 

Although the concave piston-head shows economy in 
regard to the relation of the clearance volume to the wall 
area at the moment of explosive combustion, it may be 
clearly seen that its concavity increases its surface area 
and its capacity for absorbing heat, for which there is 
no provision for cooling the piston, save its contact with 
the walls of the cylinder and the slight air cooling of its 
back by its reciprocal motion. For this reason the con- 
cave piston-head has not been generally adopted and the 
concave cylinder-head, as shown in Fig. 19, with a flat 



Mercedes Aviation Engine 



77 



Exhaust 

Valve 



Con to. v e 

Piston lop- 



Sump Cooling--~zz^\ 
■Ribs 



Inlet Valve 




^.-Approximately 
Spherical 
Chamber 



.-Carburetor 



^Connecting 
Rod 



'"Oil Sump 



Fig. 20. — Mercedes Aviation Engine Cylinder Section Showing Approximately 
Spherical Combustion Chamber and Concave Piston Top. 



78 Aviation Engines 

piston-head is the latest and best practice in airplane 
engine construction. 

The practical application of the principle just outlined 
to one of the most efficient airplane motors ever designed, 
the Mercedes, is clearly outlined at Fig. 20. 



HEAT LOSSES TO COOLING WATER 

The mean temperature of the wall surface of the com- 
bustion chamber and cylinder, as indicated by the tem- 
peratures of the circulating water, has been found to be 
an important item in the economy of the gas-engine. 
Dugald Clerk, in England, a high authority in practical 
work with the gas-engine, found that 10 per cent, of the 
gas for a stated amount of power was saved by using 
water at a temperature in which the ejected water from 
the cylinder- jacket was near the boiling-point, and ven- 
tures the opinion that a still higher temperature for the 
circulating water may be used as a source of economy. 
This could be made practical in the case of aviation en- 
gines by adjusting the air-cooling surface of the radiator 
so as to maintain the inlet water at just below the boiling 
point, and by the rapid circulation induced by the pump 
pressure, to return the water from the cylinder- jacket a 
few degrees above the boiling point. The thermal dis- 
placement systems of cooling employed in automobiles 
are working under more favorable temperature conditions 
than those engines in which cooling is more energetic. 

For a given amount of heat taken from the cylinder 
by the largest volume of circulating water, the difference 
in temperature between inlet and outlet of the water- 
jacket should be the least possible, and this condition of 
the water circulation gives a more even temperature to 
all parts of the cylinder; while, on the contrary, a cold- 
water supply, say at 60° F., so slow as to allow the ejected 
water to flow off at a temperature near the boiling-point, 
must make a great difference in temperature between the 
bottom and top of the cylinder, with a loss in economy 



Heat Losses to Cooling Water 79 

in gas and other fuels, as well as in water, if it is ob- 
tained by measurement. 

From the foregoing considerations of losses and ineffi- 
ciencies, we find that the practice in motor design and 
construction has not yet reached the desired perfection 
in its cycular operation. Step by step improvements have 
been made with many changes in design though many 
have been without merit as an improvement, farther than 
to gratify the longings of designers for something dif- 
ferent from the other thing, and to establish a special 
construction of their own. These efforts may in time 
produce a motor of normal or standard design for each 
kind of fuel that will give the highest possible efficiency 
for all conditions of service. 



CHAPTER IV 

Engine Parts and Functions — Why Multiple Cylinder Engines Are 
Best — Describing Sequence of Operations — Simple Engines — Four 
and Six Cylinder Vertical Tandem Engines — Eight and Twelve 
Cylinder V Engines — Radial Cylinder Arrangement — Rotary Cylin- 
der Forms. 

ENGINE PARTS AND FUNCTIONS 

The principal elements of a gas engine are not diffi- 
cult to understand and their functions are easily defined. 
In place of the barrel of the gun one has a smoothly 
machined cylinder in which a small cylindrical or barrel- 
shaped element fitting the bore closely may be likened to 
a bullet or cannon ball. It differs in this important 
respect, however, as while the shot is discharged from 
the mouth of the cannon the piston member sliding inside 
of the main cylinder cannot leave it, as its movements 
back and forth from the open to the closed end and back 
again are limited by simple mechanical connection or link- 
age which comprises crank and connection rod. It is by 
this means that the reciprocating movement of the piston 
is transformed into a rotary motion of the crank-shaft. 

The fly-wheel is a heavy member attached to the crank- 
shaft of an automobile engine which has energy stored 
in its rim as the member revolves, and the momentum 
of this revolving mass tends to equalize the intermittent 
pushes on the piston head produced by the explosion of 
the gas in the cylinder. In aviation engines, the weight 
of the propeller or that of rotating cylinders themselves 
performs the duty of a fly-wheel, so no separate member 
is needed. If some explosive is placed in the chamber 
formed by the piston and closed end of the cylinder and 
exploded, the piston would be the only part that would 
yield to the pressure which would produce a downward 
movement. As this is forced down the crank-shaft is 

80 



82 Aviation Engines 

turned by the connecting rod, and as this part is hinged 
at both ends it is free to oscillate as the crank turns, and 
thus the piston may slide back and forth while the crank- 
shaft is rotating or describing a curvilinear path. 

In addition to the simple elements described it is evi- 
dent that a gasoline engine must have other parts. The 
most important of these are the valves, of which there are 
generally two to each cylinder. One closes the passage 
connecting to the gas supply and opens during one stroke 
of the piston in order to let the explosive gas into the 
combustion chamber. The other member, or exhaust 
valve, serves as a cover for the opening through which 
the burned gases can leave the cylinder after their work 
is done. The spark plug is a simple device which may 
be compared to the fuse or percussion cap of the cannon. 
It permits one to produce an electric spark in the cyl- 
inder when the piston is at the best point to utilize the 
pressure which obtains when the compressed gas is fired. 
The valves are open one at a time, the inlet valve being 
lifted from its seat while the cylinder is filling and the 
exhaust valve is opened when the cylinder is being cleared. 
They are normally kept seated by means of compression 
springs. In the simple motor shown at Fig. 5, the exhaust 
valve is operated by means of a pivoted bell crank rocked 
by a cam which turns at half the speed of the crank-shaft. 
The inlet valve operates automatically, as will be ex- 
plained in proper sequence. 

In order to obtain a perfectly tight combustion cham- 
ber, both intake and exhaust valves are closed before the 
gas is ignited, because all of the pressure produced by 
the exploding gas is to be directed against the top of 
the movable piston. When the piston reaches the bottom 
of its power stroke, the exhaust valve is lifted by means 
of the bell crank which is rocked because of the point or 
lift on the cam. The cam-shaft is driven by positive 
gearing and revolves at half the engine speed. The ex- 
haust valve remains open during the whole of the return 
stroke of the piston, and as this member moves toward 



Why Multiple Cylinder Forms Are Best 83 

the closed end of the cylinder it forces out burned gases 
ahead of it, through the passage controlled by the exhaust 
valve. The cam-shaft is revolved at half the engine speed 
because the exhaust valve is raised from its seat during 
only one stroke out of four, or only once every two revo- 
lutions. Obviously, if the cam was turned at the same 
speed as the crank-shaft it would remain open once every 
revolution, whereas the burned gases are expelled from 
the individual cylinders only once in two turns of the 
crank-shaft. 

WHY MULTIPLE CYLINDER FORMS ARE BEST 

Owing to the vibration which obtains from the heavy 
explosion in the large single-cylinder engines used for 
stationary power other forms were evolved in which the 
cylinder was smaller and power obtained by running the 
engine faster, but these are suitable only for very low 
powers. 

When a single-cylinder engine is employed a very 
heavy fly-wheel is needed to carry the moving parts 
through idle strokes necessary to obtain a power im- 
pulse. For this reason automobile and aircraft design- 
ers must use more than one cylinder, and the tendency 
is to produce power by frequently occurring light im- 
pulses rather than by a smaller number of explosions 
having greater force. When a single-cylinder motor is 
employed the construction is heavier than is needed with 
a multiple-cylinder form. Using two or more cylinders 
conduces to steady power generation and a lessening of 
vibration. Most modern motor cars employ four-cylinder 
engines because a power impulse may be secured twice 
every revolution of the crank-shaft, or a total of four- 
power strokes during two revolutions. The parts are so 
arranged that while the charge of gas in one cylinder is 
exploding, those which come next in firing order are com- 
pressing, discharging the inert gases and drawing in a 
fresh charge respectively. When the power stroke is 
completed in one cylinder, the piston in that member in 



84 Aviation Engines 

which a charge of gas has just been compressed has 
reached the top of its stroke and when the gas is ex- 
ploded the piston is reciprocated and keeps the crank- 
shaft turning. When a multiple-cylinder engine is used 
the fly-wheel can be made much lighter than that of the 
simpler form and eliminated altogether in some designs. 
In fact, many modern multiple-cylinder engines develop- 
ing 300 horse-power weigh less than the early single- and 
double-cylinder forms which developed but one-tenth or 
one-twentieth that amount of energy. 

DESCRIBING SEQUENCE OF OPERATIONS 

Referring to Fig. 22, A, the sequence of operation in 
a single-cylinder motor can be easily understood. As- 
suming that the crank-shaft is turning in the direction 
of the arrow, it will be seen that the intake stroke comes 
first, then the compression, which is followed by the power 
impulse, and lastly the exhaust stroke. If two cylinders 
are used, it is possible to balance the explosions in such 
a way that one will occur each revolution. This is true 
with either one of two forms of four-cycle motors. At 
B, a two-cylinder vertical engine using a crank-shaft in 
which the crank-pins are on the same plane is shown. 
The two pistons move up and down simultaneously. Re- 
ferring to the diagram describing the strokes, and assum- 
ing that the outer circle represents the cycle of operations 
in one cylinder while the inner circle represents the se- 
quence of events in the other cylinder, while cylinder 
No. 1 is taking in a fresh charge of gas, cylinder No. 2 
is exploding. When cylinder No. 1 is compressing, cyl- 
inder No. 2 is exhausting. During the time that the charge 
in cylinder No. 1 is exploded, cylinder No. 2 is being filled 
with fresh^gas. While the exhaust gases are being dis- 
charged from cylinder No. 1, cylinder No. 2 is compressing 
the gas previously taken. 

The same condition obtains when the crank-pins are 
arranged at one hundred and eighty degrees and the cyl- 
inders are opposed, as shown at C. The reason that the 






Sequence of Operations 



85 



i^ 



/H t^V^ jti 



\J \J 

Single Cylinder 




/V-U\ 



M H 



~ 



Two Cylinder Vertical 
Crankpins on Same Plane 




S 



~^ 



Two Cylinder, Opposed 
Crankpins At 180 Degrees 




Fig. 22. — Diagrams Illustrating Sequence of Cycles in One- and Two-Cylinder 
Engines Showing More Uniform Turning Effort on Crank-Shaft with 
Two-Cylinder Motors. 



86 Aviation Engines 

two-cylinder opposed motor is more popular than that 
having two vertical cylinders is that it is difficult to bal- 
ance the construction shown at B, so that the vibration 
will not be excessive. The two-cylinder opposed motor 
has much less vibration than the other form, and as the 
explosions occur evenly and the motor is a simple one 
to construct, it has been very popular in the past on 
light cars and has received limited application on some 
early, light airplanes. 

To demonstrate very clearly the advantages of multi- 
ple-cylinder engines the diagrams at Fig. 23 have been 
prepared. At A, a three-cylinder motor, having crank- 
pins at one hundred and twenty degrees, which means that 
they are spaced at thirds of the circle, we have a form 
of construction that gives a more even turning than that 
possible with a two-cylinder engine. Instead of one ex- 
plosion per revolution of the crank-shaft, one will obtain 
three explosions in two revolutions. The manner in which 
the explosion strokes occur and the manner they overlap 
strokes in the other cylinder is shown at A. Assuming 
that the cylinders fire in the following order, first No. 1, 
then No. 2, and last No. 3, we will see that while cylinder 
No. 1, represented by the outer circle, is on the power 
stroke, cylinder No. 3 has completed the last two-thirds 
of its exhaust stroke and has started on its intake stroke. 
Cylinder No. 2, represented by the middle circle, during 
this same period has completed its intake stroke and two- 
thirds of its compression stroke. A study of the diagram 
will show that there is an appreciable lapse of time be- 
tween each explosion. 

Three-cylinder engines are not used on aircraft at the 
present time, though Bleriot's flight across the British 
Channel was made with a three-cylinder Anzani motor. 
It was not a conventional form, however. The three-cyl- 
inder engine is practically obsolete at this time for any 
purpose except " penguins " or school machines that are 
incapable of flight and which are used in some French 
training schools for aviators. 



Four- and Six-Cylinder Engines 



87 



Firing Order 1,3,2 



B 



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£ 



dE 



i i 



RSP! 



77?ree Cylinder, Cranks At 120 Degrees 




Firing Ordsr 1.2.4,3 




Four Cylinder, Cranks At 180 Degrees 



First Revolution Second Revolution 
180 180" 180 180" 




Firing Order 1,5.3,6,2,4 



m^ \ 



•fi%M4.p? & 




Fig. 23. — Diagrams Demonstrating Clearly Advantages which Obtain when 
Multiple-Cylinder Motors are Used as Power Plants. 



88 Aviation Engines 



FOUK- AND SIX-CYLINDER ENGINES 

In the four-cylinder engine operation which is shown 
at Fig. 23, B, it will be seen that the power strokes follow 
each other without loss of time, and one cylinder begins 
to fire and the piston moves down just as soon as the 
member ahead of it has completed its power stroke. In 
a four-cylinder motor, the crank-pins are placed at one 
hundred and eighty degrees, or on the halves of the crank 
circle. The crank-pins for cylinders No. 1 and No. 4 are 
on the same plane, while those for cylinders No. 2 and 
No. 3 also move in unison. The diagram describing se- 
quence of operations in each cylinder is based on a firing 
order of one, two, four, three. The outer circle, as in 
previous instances, represents the cycle of operations in 
cylinder one. The next one toward the center, cylinder 
No. 2, the third circle represents the sequence of events 
in cylinder No. 3, while the inner circle outlines the strokes 
in cylinder four. The various cylinders are working as 
follows : 

1. 2. 3. 4. 

Explosion Compression Exhaust Intake 

Exhaust Explosion Intake Compression 

Intake Exhaust Compression Explosion 

Compression Intake Explosion Exhaust 

It will be obvious that regardless of the method of 
construction, or the number of cylinders employed, ex- 
actly the same number of parts must be used in each 
cylinder assembly and one can conveniently compare 
any multiple-cylinder power plant as a series of single- 
cylinder engines joined one behind the other and so 
coupled that one will deliver power and produce useful 
energy at the crank-shaft where the other leaves off. 
The same fundamental laws governing the action of a 
single cylinder obtain when a number are employed, and 
the sequence of operation is the same in all members, ex- 
cept that the necessary functions take place at different 



Why Multiple Cylinder Forms Are Best 89 

times. If, for instance, all the cylinders of a four-cylin- 
der motor were fired at the same time, one would obtain 
the same effect as though a one-piston engine was used, 
which had a piston displacement equal to that of the four 
smaller members. As is the case with a single-cylinder 
engine, the motor would be out of correct mechanical bal- 
ance because all the connecting rods would be placed on 
crank-pins that lie in the same plane. A very large fly- 
wheel would be necessary to carry the piston through the 
idle strokes, and large balance weights would be fitted to 
the crank-shaft in an effort to compensate for the weight 
of the four pistons, and thus reduce vibratory stresses 
which obtain when parts are not in correct balance. 

There would be no advantage gained by using four 
cylinders in this manner, and there would be more loss of 
heat and more power consumed in friction than in a one- 
piston motor of the same capacity. This is the reason 
that when four cylinders are used the arrangement of 
crank-pins is always as shown at Fig. 23, B — i.e., two 
pistons are up, while the other two are at the bottom of 
the stroke. With this construction, we have seen that it 
is possible to string out the explosions so that there will 
always be one cylinder applying power to the crank-shaft. 
The explosions are spaced equally. The parts are in 
correct mechanical balance because two pistons are on the 
upstroke while the other two are descending. Care is 
taken to have one set of moving members weigh exactly 
the same as the other. With a four-cylinder engine one 
has correct balance and continuous application of energy. 
This insures a smoother running motor which has greater 
efficiency than the simpler one-, two-, and three-cylinder 
forms previously described. Eliminating the stresses 
which would obtain if we had an unbalanced mechanism 
and irregular power application makes for longer life. 
Obviously a large number of relatively light explosions 
will produce less wear and strain than would a lesser 
number of powerful ones. As the parts can be built lighter 
if the explosions are not heavy, the engine can be oper- 



90 



Aviation Engines 



ated at higher rotative speeds than when large and cum- 
bersome members are utilized. Four-cylinder engines 
intended for aviation work have been built according to 
the designs shown at Fig. 24, but these forms are un- 
conventional and seldom if ever used. 

The six-cylinder type of motor, the action of which is 
shown at Fig. 23, C, is superior to the four-cylinder, inas- 




Radial Cylinder 
Arrangement 



Two Sets of Opposed Cylinders 



Fig. 24. — Showing Three Possible Though Unconventional Arrangements of 
Four-Cylinder Engines. 



much as the power strokes overlap, and instead of having 
two explosions each revolution we have three explosions. 
The conventional crank- shaft arrangement in a six-cylinder 
engine is just the same as though one used two three- 
cylinder shafts fastened together, so pistons 1 and 6 are 
on the same plane as are pistons 2 and 5. Pistons 3 and 
4 also travel together. With the cranks arranged as out- 
lined at Fig. 23, C, the firing order is one, five, three, six, 
two, four. The manner in which the power strokes overlap 
is clearly shown in the diagram. An interesting com- 



Why Multiple Cylinder Forms Are Best 91 



parison is also made in the diagrams at Fig. 25 and in the 
upper corner of Fig. 23, C. 

A rectangle is divided into four columns ; each of these 
corresponds to one hundred and eighty degrees, or half a 
revolution. Thus the first revolution of the crank-shaft 
is represented by the first two columns, while the second 
revolution is represented by the last two. Taking the por- 



THE APPLICATION OF POWER IN THE SIX-CYLINDER MOTOR 

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THE APPLICATION OF POWER IN THE FOUR-CYLINDER MOTOR 

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THIS DIAGRAM REPRESENTS ONE "CYCLE" IN WHICH THE PISTON TRAVELS 20 INCHES 

M T 0R .^——REPRESENTS POWER I 1 REPRESENTS NO POWER 

\ CYL 
2 CYL 
4 CYL 



6 CYL 




Fig. 25. — Diagrams Outlining Advantages of Multiple Cylinder Motors, and 
Why They Deliver Power More Evenly Than Single Cylinder Types. 

tion of the diagram which shows the power impulse in a 
one-cylinder engine, we see that during the first revolution 
there has been no power impulse. During the first half 
of the second revolution, however, an explosion takes place 
and a power impulse is obtained. The last portion of the 
second revolution is devoted to exhausting the burned 
gases, so that there are three idle strokes and but one 
power stroke. The effect when two cylinders are employed 
is shown immediately below. 



92 



Aviation Engines 



Here we have one explosion during the first half of the 
first revolution in one cylinder and another during the first 
half of the second revolution in the other cylinder. "With 
a four-cylinder engine there is an explosion each half revo- 
lution, while in a six-cylinder engine there is one and one- 
half explosions during each half revolution. When six 



Diagrams Show inoj Duration of Events 
for a Four Stroke Cycle. Six Cylinder Engine 

When Exhaust Valves open 45° early 
and cio$e V' '/ate. and Inlet 
'/ate and 




Note.- Read Figs. 3&4 
from Centers outward 



Is+S+r 2nd S+r 3rd 5+r 4th St 



1st Revolution ONE CYCLE 
720<-0° 



2nd Revolution 




180° 



Fig. 3 



540 ° 



Fig. 26. — Diagrams Showing Duration of Events for a Four-Stroke Cycle, 

Six-Cylinder Engine. 

cylinders are used there is no lapse of time between power 
impulses, as these overlap' and a continuous and smooth- 
turning movement is imparted to the crank shaft. The 
diagram shown at Fig. 26, prepared by E. P. Pulley, can 
be studied to advantage in securing an idea of the coor- 
dination of effort that takes place in an engine of the six- 
cylinder type. 



Actual Duration of Cycle Functions 



93 



ACTUAL DURATION" OF DIFFERENT STROKES 

In the diagrams previously presented the writer has 
assumed, for the sake of simplicity, that each stroke takes 
place during half of one revolution of the crank-shaft, 



Inlet Valve 
Opens 7 %'Past 
Center-Upper^ 



Exhaust Valve 




Inlet Valve 



Center-Lower 



Exhaust Valve 
Opens 7" Before 
Center-Lower 



Fig. 27. — Diagram Showing Actual Duration of Different Strokes in Degrees. 



which corresponds to a crank-pin travel of one hundred 
and eighty degrees. The actual duration of these strokes 
is somewhat different. For example, the inlet stroke is 
usually a trifle more than a half revolution, and the exhaust 
is always considerably more. The diagram showing the 
comparative duration of the strokes is shown at Fig. 27- 



94 



Aviation Engines 



The inlet valve opens ten degrees after the piston starts 
to go down and remains open thirty degrees after the 
piston has reached the bottom of its stroke. This means 
that the suction stroke corresponds to a crank-pin travel 
of two hundred degrees, while the compression stroke is 
measured by a movement of but one hundred and fifty 
degrees. It is common practice to open the exhaust valve 
before the piston reaches the end of the power stroke so 
that the actual duration of the power stroke is about one 
hundred and forty degrees, while the exhaust stroke cor- 
responds to a crank-pin travel of two hundred and twenty- 
five degrees. In this diagram, which represents proper 




Revolutions 



Fig. 28. — Another Diagram to Facilitate Understanding Sequence of 
Functions in Six-Cylinder Engine. 

time for the valves to open and close, the dimensions in 
inches given are measured on the fly-wheel and apply only 
to a certain automobile motor. If the fly-wheel were 
smaller ten degrees would take up less than the dimensions 
given, while if the fly-wheel was larger a greater space on 
its circumference would represent the same crank-pin 
travel. Aviation engines are timed by using a timing disc 
attached to the crank-shaft as they are not provided with 
fly-wheels. Obviously, the distance measured in inches 
will depend upon the diameter of the disc, though the 
number of degrees interval would not change. 



EIGHT- AND TWELVE-CYLINDER V ENGINES 

Those who have followed the development of the gaso- 
line engine will recall the arguments that were made when 
the six-cylinder motor was introduced at a time that the 



Vee 'Engine Advantages 



95 



four-cylinder type was considered standard. The arrival 
of the eight-cylinder has created similar futile discussion 
of its practicability as this is so clearly established as to 
be accepted without question. It has been a standard 
power plant for aeroplanes for many years, early expo- 
nents having been the Antoinette, the Woolsley, the 
Eenault, the E. N. V. in Europe and the Curtiss in the 
United States. 

The reason the V type shown at Fig. 29, A is favored is 
that the "all-in-line form" which is shown at Fig. 29, B is 




Fig. 29. — Types of Eight-Cylinder Engines Showing the Advantage of the 
V Method of Cylinder Placing. 

not practical for aircraft because of its length. Compared 
to the standard four-cylinder engine it is nearly twice as 
long and it required a much stronger and longer crank- 
shaft. It will be evident that it could not be located to 
advantage in the airplane fuselage. These undesirable 
factors are eliminated in the V type eight-cylinder motor, 
as it consists of two blocks of four cylinders each, so ar- 
ranged that one set or block is at an angle of forty-five 
degrees from the vertical center line of the motor, or at 
an angle of ninety degrees with the other set. This 
arrangement of cylinders produces a motor that is no 



96 Aviation Engines 

longer than a four-cylinder engine of half the power 
would be. 

Apparently there is considerable misconception as to 
the advantage of the two extra cylinders of the eight as 
compared with the six-cylinder. It should be borne in mind 
that the multiplication in the number of cylinders noticed 
since the early days of automobile development has not 
been for solely increasing the power of the engine, but to 
secure a more even turning movement, greater flexibility 










































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30" 60" 90" I2Q" 150" 160" £10" 2*0" 270" 300" 330" 360" 30" 60" 90" 120* ISO' 180" 210" 240" 270' 300' 330' 360" 
Comparative torque diagrams of four, alx and eight-cylinder motors, showing Increaae In uniformity with added cylinders. 



Fig. 30. — Curves Showing Torque of Various Engine Types Demonstrate 
Graphically Marked Advantage of the Eight-Cylinder Type. 



and to eliminate destructive vibration. The ideal internal 
combustion motor is the one having the most uniform turn- 
ing movement with the least mechanical friction loss. 
Study of the torque outlines or plotted graphics shown 
at Figs. 25 and 30 will show how multiplication of cylinders 
will produce steady power delivery due to overlapping 
impulses. The most practical form would be that which 
more nearly conforms to the steady running produced by 
a steam turbine or electric motor. The advocates of the 
eight-cylinder engine bring up the item of uniform torque 



Vee Engine Advantages 97 

as one of the most important advantages of the eight- 
cylinder design. A number of torque diagrams are shown 
at Fig. 30. While these appear to be deeply technical, 
they may be very easily followed when their purpose is 
explained. At the top is shown the torque diagram of a 
single-cylinder motor of the four-cycle type. The high 




Fig. 31 — Diagrams Showing How Increasing Number of Cylinders Makes 
for More Uniform Power Application. 

point in the line represents the period of greatest torque 
or power generation, and it will be evident that this occurs 
early in the first revolution of the crank-shaft. Below this 
diagram is shown a similar curve except that it is pro- 
duced by a four-cylinder engine. Inspection will show that 
the turning moment is much more uniform than in the 



98 Aviation Engines 

single cylinder; similarly, the six-cylinder diagram is an 
improvement over the four, and the eight-cylinder diagram 
is an improvement over the six-cylinder. 

The reason that practically continuous torque is ob- 
tained in an eight-cylinder engine is that one cylinder fires 
every ninety degrees of crank-shaft rotation, and as each 
impulse lasts nearly seventy-five per cent, of the stroke, 
one can easily appreciate that an engine that will give four 
explosions per revolution of the crank-shaft will run more 
uniformly than one that gives but three explosions per 
revolution, as the six-cylinder does, and will be twice as 
smooth running as a four-cylinder, in which but two explo- 
sions occur per revolution of the crank-shaft. The com- 
parison is so clearly shown in graphical diagrams and in 
Fig. 31 that further description is unnecessary. 

Any eight-cylinder engine may be considered a "twin- 
four," twelve-cylinder engines may be considered "twin 
sixes." 

The only points in which an eight-cylinder motor dif- 
fers from a four-cylinder is in the arrangement of the 
connecting rod, as in many designs it is necessary to have 
two rods working from the same crank-pin. This difficulty 
is easily overcome in some designs by staggering the cylin- 
ders and having the two connecting rod big ends of con- 
ventional form side by side on a common crank-pin. In 
other designs one rod is a forked form and works on the 
outside of a rod of the regular pattern. Still another 
method is to have a boss just above the main bearing on 
one connecting rod to which the lower portion of the con- 
necting rod in the opposite cylinder is hinged. As the 
eight-cylinder engine may actually be made lighter than 
the six-cylinder of equal power, it is possible to use smaller 
reciprocating parts, such as pistons, connecting rods and 
valve gear, and obtain higher engine speed with practically 
no vibration. The firing order in nearly every case is the 
same as in a four-cylinder except that the explosions occur 
alternately in each set of cylinders. The firing order of 
an eight-cylinder motor is apt to be confusing to the 




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99 



100 



Aviation Engines 



motorist, especially if one considers that there are eight 
possible sequences. The majority of engineers favor the 
alternate firing from side to side. Firing orders will be 
considered in proper sequence. 

The demand of aircraft designers for more power has 
stimulated designers to work out twelve-cylinder motors. 




Fig. 33. — The Hall-Scott Four-Cylinder 100 Horse-Power Aviation Motor. 



These are high-speed motors incorporating all recent fea- 
tures of design in securing light reciprocating parts, large 
valve openings, etc. The twelve-cylinder motor incorpor- 
ates the best features of high-speed motor design and there 
is no need at this time to discuss further the pros and cons 
of the twelve-cylinder versus the eight or six, because it 
is conceded by all that there is the same degree of steady 
power application in the twelve over the eight as there 
would be in the eight over the six. The question resolves 




Propeller D r t ve'fe j J c 
Reduction GedMMg/ 



Fig. 34.— Two Views of the Duesenberg Sixteen Valve Four-Cylinder 
Aviation Motor. 
101 



102 



Aviation Engines 



itself into Having a motor of high power that will run with 
minimum vibration and that produces smooth action. This 
is well shown by diagrams at Fig. 31. It should be re- 
membered that if an eight-cylinder engine^ will give four 
explosions per revolution of the fly-wheel, a twelve-cylinder 
type will give six explosions per revolution, and instead 
of the impulses coming 90 degrees crank travel apart, as 
in the case of the eight-cylinder, these will come but 60 



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Fig. 35. — The Hall-Scott Six-Cylinder Aviation Engine. 



degrees of crank travel apart in the case of the twelve- 
cylinder. For this reason, the cylinders of a twelve are 
usually separated by 60 degrees while the eight has the 
blocks spaced 90 degrees apart. The comparison can be 
easily made hy comparing the sectional views of Vee 
engines at Fig. 32. When one realizes that the actual 
duration of the power stroke is considerably greater than 
120 degrees crank travel, it will be apparent that the 
overlapping of explosions must deliver a very uniform 
application of power. Vee engines have been devised 



Radial Cylinder Arrangements 



103 



having the cylinders spaced bnt 45 degrees apart, but the 
explosions cannot be timed at eqnal intervals as when 90 
degrees separate the cylinder center lines. 



RADIAL CYLINDER ARRAXGEMEXTS 

While the fixed cylinder forms of engines, having the 
cylinders in tandem in the fonr- and six-cylinder models 
as shown at Figs. 33 to 35 inclnsive and the eight-cylinder 
V types as outlined at Figs. 36 and 37 have been generally 
used and are most in favor at the present time, other forms 
of motors having unconventional cylinder arrangements 
have been devised, though most of these are practically 





'iew of Power D« 



Fig. 36. — The Curtiss Eight-Cylinder, 200 Horse-Power Aviation Engine. 



104 



Aviation Engines 



obsolete. While many methods of decreasing weight and 
increasing mechanical efficiency of a motor are known to 
designers, one of the first to be applied to the construction 
of aeronautical power plants was an endeavor to group 
the components, which in themselves were not extremely 
light, into a form that would be considerably lighter than 
the conventional design. As an example, we may consider 
those multiple-cylinder forms in which the cylinders are 





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Fig. 37.— The Sturtevant Eight-Cylinder, High Speed Aviation Motor. 



disposed around a short crank-case, either radiating from 
a. common center as at Fig. 38 or of the fan shape shown 
at Fig. 39. This makes it possible to use a crank-case but 
slightly larger than that needed for one or two cylinders 
and it also permits of a corresponding decrease in length 
of the crank-shaft. The weight of the engine is lessened 
because of the reduction in crank-shaft and crank-case 
weight and the elimination of a number of intermediate 
bearings and their supporting webs which would be neces- 
sary with the usual tandem construction. While there are 
six power impulses to every two revolutions of the crank- 



Radial Cylinder Arrangements 



105 



shaft, in the six-cylinder engine, they are not evenly spaced 
as is possible with the conventional arrangement. 

In the Anzani form, which is shown at Fig. 38, the crank- 
case is stationary and a revolving crank-shaft is employed 
as in conventional construction. The cylinders are five 




Fig. 38. — Anzani 40-50 Horse-Power Five-Cylinder Air Cooled Engine. 

in number and the engine develops 40 to 50 H. F. with a 
weight of 72 kilograms or 158.4 lbs. The cylinders are of 
the usual air-cooled form having cooling flanges only part 
of the way down the cylinder. By using five cylinders it 
is possible to have the power impulses come regularly, 
they coming 145° crank-shaft travel apart, the crank-shaft 
making two turns to every five explosions. The balance 
is good and power output regular. The valves are 



106 



Aviation Engines 



placed directly in the cylinder head and are operated by 
a common pushrod. Attention is directed to the novel 
method of installing the carburetor which supplies the mix- 
ture to the engine base from which inlet pipes radiate to 
the various cylinders. This engine is used on French 
school machines. 

In the form shown at Fig. 39 six cylinders are used, 
all being placed above the crank-shaft center line. This 




Fig. 39. — Unconventional Six-Cylinder Aircraft Motor of Masson Design. 

engine is also of the air-cooled form and develops 50 H. P. 
and weighs 105 kilograms, or 231 lbs. The carburetor is 
connected to a manifold .casting attached to the engine base 
from which the induction pipes radiate to the various 
cylinders. The propeller design and size relative to the 
engine is clearly shown in this view. While flights have 
been made with both of the engines described, this method 
of construction is not generally followed and has been 
almost entirely displaced abroad by the revolving motors 
or by the more conventional eight-cylinder V engines. 
Both of the engines shown were designed about eight years 



Rotary Cylinder Engir^es 



107 



ago and would be entirely too small and weak for use in 
modern airplanes intended for active duty. 



ROTARY EXGLN-ES 



Eotary engines such as shown at Fig. 40 are generally 
associated with the idea of light construction and it is 




Fig. 40. — The Gnome Fourteen-Cylinder Revolving Motor. 

rather an interesting point that is often overlooked in 
connection with the application of this idea to flight 
motors, that the reason why rotary engines are popularly 
supposed to be lighter than the others is because they form 
their own fly-wheel, yet on aeroplanes, engines are seldom 
fitted with a fly-wheel at all. As a matter of fact the 



108 # Aviation Engines 

Gnome engine is not so light because it is a rotary motor, 
and it is a rotary motor because the design that has 
been adopted as that most conducive to lightness is 
also most suited to an engine working in this way. 
The cylinders could be fixed and crank-shaft revolve 
without increasing the weight to any extent. There 
are two prime factors governing the lightness of an 
engine, one being the initial design, and the other the 
quality of the materials employed. The consideration 
of reducing weight by cutting away metal is a subsidi- 
ary method that ought not to play a part in standard 
practice, however useful it may be in special cases. In 
the Gnome rotary engine the lightness is entirely due to 
the initial design and to the materials employed in manu- 
facture. Thus, in the first case, the engine is a radial 
engine, and has its seven or nine cylinders spaced equally 
around a crank-chamber that is no wider or rather longer 
than would be required for any one of the cylinders. 
This shortening of the crank-chamber not only effects 
a considerable saving of weight on its own account, but 
there is a corresponding saving in the shafts and other 
members, the dimensions of which are governed by the 
size of the crank-chamber. With regard to materials, 
nothing but steel is used throughout, and most of the metal 
is forged chrome nickel steel. The beautifully steady 
running of the engine is largely due to the fact that there 
are literally no reciprocating parts in the absolute sense, 
the apparent reciprocation between the pistons and cylin- 
ders being solely a relative reciprocation since both travel 
in circular paths, that of the pistons, however, being 
electric by one-half of the stroke length to that of the 
cylinder. 

"While the Gnome engine has many advantages, on the 
other hand the head resistance offered by a motor of this 
type is considerable; there is a large waste of lubricating 
oil due to the centrifugal force which tends to throw the 
oil away from the cylinders; the gyroscopic effect of the 
rotary motor is detrimental to the best working of the 



Rotary Cylinder Engines 109 

aeroplane, and moreover it requires about seven per cent, 
of the total power developed by the motor to drive the 
revolving cylinders around the shaft. Of necessity, the 
compression of this type of motor is rather low, and an 
additional disadvantage manifests itself in the fact that 
there is as yet no satisfactory way of muffling the rotary 
type of motor. The modern Gnome engine has been widely 
copied in various European countries, but its design was 
originated in America, the early Adams-Farwell engine 
being the pioneer form. It has been made in seven- and 
nine-cylinder types and forms of double these numbers. 
The engine illustrated at Fig. 40 is a four teen-cylinder 
form. The simple engines have an odd number of cylin- 
ders in order to secure evenly spaced explosions. In the 
seven-cylinder, the impulses come 102.8° apart. In the 
nine-cylinder form, the power strokes are spaced 80° apart. 
The fourteen-cylinder engine is virtually two seven-cylin- 
der types mounted together, the cranks being just the 
same as in a double cylinder opposed motor, the explosions 
coming 51.4° apart; while in the eighteen-cylinder model 
the power impulses come every 40° cylinder travel. Other 
rotary motors have been devised, such as the Le Rhone 
and the Clerget in France and several German* copies of 
these various types. The mechanical features of these 
motors will be fully considered later. 



CHAPTER V 

Properties of Liquid Fuels — Distillates of Crude Petroleum — Principles 
of Carburetion Outlined — Air Needed to Burn Gasoline — What 
a Carburetor Should Do — Liquid Fuel Storage and Supply — 
Vacuum Fuel Feed — Early Vaporizer Forms — Development of 
Float Feed Carburetor — Maybach's Early Design — Concentric 
Float and Jet Type — Schebler Carburetor — Claudel Carburetor — 
Stewart Metering Pin Type — Multiple Nozzle Vaporizers- — Two- 
Stage Carburetor — Master Multiple Jet Type — Compound Nozzle 
Zenith Carburetor — Utility of Gasoline Strainers — Intake Manifold 
Design and Construction — Compensating for Various Atmospheric 
Conditions — How High Altitude Affects Power — The Diesel Sys- 
tem — Notes on Carburetor Installation — Notes on Carburetor Ad- 
justment. 

There is no appliance that has more material value 
upon the efficiency of the internal combustion motor than 
the carburetor or vaporizer which supplies the explosive 
gas to the cylinders. It is only in recent years that en- 
gineers have realized the importance of using carburetors 
that are efficient and that are so strongly and simply made 
that there will be little liability of derangement. As the 
power obtained from the gas-engine depends upon the 
combustion of fuel in the cylinders, it is evident that if 
the gas supplied does not have the proper proportions of 
elements to insure rapid combustion the efficiency of the 
engine will be low. When a gas engine is used as a sta- 
tionary installation it is possible to use ordinary illuminat- 
ing or natural gas for fuel, but when this prime mover is 
applied to automobiles or airplanes it is evident that con- 
siderable difficulty would be experienced in carrying enough 
compressed coal gas to supply the engine for even a very 
short trip. Fortunately, the development of the internal- 
combustion motor was not delayed by the lack of suitable 
fuel. 

Engineers were familiar with the properties of certain 

no 



Distillates of Crude Petroleum 111 

liquids which gave off vapors that could be mixed with air 
to form an explosive gas which burned very well in the 
engine cylinders. A very small quantity of such liquids 
would suffice for a very satisfactory period of operation. 
The problem to be solved before these liquids could be 
applied in a practical manner was to evolve suitable ap- 
paratus for vaporizing them without waste. Among the 
liquids that can be combined with air and burned, gasoline 
is the most volatile and is the fuel utilized by internal- 
combustion engines. 

The widely increasing scope of usefulness of the in- 
ternal-combustion motor has made it imperative that other 
fuels be applied in some instances because the supply of 
gasoline may in time become inadequate to supply the 
demand. In fact, abroad this fuel sells for fifty to two 
hundred per cent, more than it does in America because 
most of the gasoline used must be imported from this 
country or Russia. Because of this foreign engineers have 
experimented widely with other substances, such as alco- 
hol, benzol, and kerosene, but more to determine if they 
can be used to advantage in motor cars than in airplane 
engines. 

DISTILLATES OF CRUDE PETROLEUM 

Crude petroleum is found in small quantities in almost 
all parts of the world, but a large portion of that pro- 
duced commercially is derived from American wells. The 
petroleum obtained in this country yields more of the 
volatile products than those of foreign production, and for 
that reason the demand for it is greater. The oil fields 
of this country are found in Pennsylvania, Indiana, and 
Ohio, and the crude petroleum is usually in association 
with natural gas. This mineral oil is an agent from which 
many compounds and products are derived, and the prod- 
ucts will vary from heavy sludges, such as asphalt, to 
the lighter and more volatile components, some of which 
will evaporate very easily at ordinary temperatures. 

The compounds derived from crude petroleum are com- 



112 Aviation Engines 

posed principally of hydrogen and carbon and are termed 
" Hydrocarbons.' ' In the crude product one finds many 
impurities, such as free carbon, sulphur, and various 
earthy elements. Before the oil can be utilized it must be 
subjected to a process of purifying which is known as 
refining, and it is during this process, which is one of 
destructive distillation, that the various liquids are sepa- 
rated. The oil was formerly broken up into three main 
groups of products as follows: Highly volatile, naphtha, 
benzine, gasoline, eight to ten per cent. Light oils, such 
as kerosene and light lubricating oils seventy to eighty 
per cent. Heavy oils or residuum five to nine per cent. 
From the foregoing it will be seen that the available sup- 
ply of gasoline is determined largely by the demand exist- 
ing for the light oils forming the larger part of the 
products derived from crude petroleum. New processes 
have been recently discovered by which the lighter oils, 
such as kerosene, are reduced in proportion and that of 
gasoline increased, though the resulting liquid is neither 
the high grade, volatile gasoline known in the early days 
of motoring nor the low grade kerosene. 

PRINCIPLES OF CARBURETION OUTLINED 

The process of carburetion is combining the volatile 
vapors which evaporate from the hydrocarbon liquids with 
certain proportions of air to form an inflammable gas. 
The quantities of air needed vary with different liquids 
and some mixtures burn quicker than do other combina- 
tions of air and vapor. Combustion is simply burning and 
it may be rapid, moderate or slow. Mixtures of gasoline 
and air burn quickly, in fact the combustion is so rapid 
that it is almost instantaneous and we obtain what is 
commonly termed an " explosion.' ' Therefore the ex- 
plosion of gas in the automobile engine cylinder which 
produces the power is really a combination of chemical 
elements which produce heat and an increase in the vol- 
ume of the gas because of the increase in temperature. 

If the gasoline mixture is not properly proportioned 



Air Needed to Burn Gasoline 113 

the rate of burning will vary, and if the mixture is either 
too rich or too weak the power of the explosion is reduced 
and the amount of power applied to the piston is de- 
creased proportionately. In determining the proper pro- 
portions of gasoline and air, one must take the chemical 
composition of gasoline into account. The ordinary liquid 
used for fuel is said to contain about eight-four per cent, 
carbon and sixteen per cent, hydrogen. Air is composed 
of oxygen and nitrogen and the former has a great affinity, 
or combining power, with the two constituents of hydro- 
carbon liquids. Therefore, what we call an explosion is 
merely an indication that oxygen in the air has combined 
with the carbon and hydrogen of the gasoline. 

AIR NEEDED TO BURN GASOLINE 

In figuring the proper volume of air to mix with a 
given quantity of fuel, one takes into account the fact that 
one pound of hydrogen requires eight pounds of oxygen 
to burn it, and one pound of carbon needs two and one- 
third pounds of oxygen to insure its combustion. Air is 
composed of one part of oxygen to three and one-half por- 
tions of nitrogen by weight. Therefore for each pound of 
oxygen one needs to burn hydrogen or carbon four and 
one-half pounds of air must be allowed. To insure com- 
bustion of one pound of gasoline which is composed of 
hydrogen and carbon we must furnish about ten pounds 
of air to burn the carbon and about six pounds of air to 
insure combustion of hydrogen, the other component of 
gasoline. This means that to burn one pound of gasoline 
one must provide about sixteen pounds of air. 

While one does not usually consider air as having much 
weight, at a temperature of sixty-two degrees Fahrenheit 
about fourteen cubic feet of air will weigh a pound, and 
to burn a pound of gasoline one would require about two 
hundred cubic feet of air. This amount will provide for 
combustion theoretically, but it is common practice to 
allow twice this amount because the element nitrogen, 
which is the main constituent of air, is an inert gas and 



114 Aviation Engines 

instead of aiding combustion it acts as a deterrent of 
burning. In order to be explosive, gasoline vapor must 
be combined with definite quantities of air. Mixtures that 
are rich in gasoline ignite quicker than those which have 
more air, but these are only suitable when starting or 
when running slowly, as a rich mixture ignites much 
quicker than a weak mixture. The richer mixture of 
gasoline and air not only burns quicker but produces the 
most heat and the most effective pressure in pounds per 
square inch of piston top area. 

The amount of compression of the charge before igni- 
tion also has material bearing on the force of the explo- 
sion. The higher the degree of compression the greater 
the force exerted by the rapid combustion of the gas. It 
may be stated that as a general thing the maximum ex- 
plosive pressure is somewhat more than four times .the 
compression pressure prior to ignition. A charge com- 
pressed to sixty pounds will have a maximum of approxi- 
mately two hundred and forty pounds; compacted to 
eighty pounds it will produce a pressure of about three 
hundred pounds on each square inch of piston area at 
the beginning of the power stroke. Mixtures varying 
from one part of gasoline vapor to four of air to others 
having one part of gasoline vapor to thirteen of air can 
be ignited, but the best results are obtained when the 
proportions are one to five or one to seven, as this mix- 
ture is said to be the one that will produce the high- 
est temperature, the quickest explosion, and the most 
pressure. 

WHAT A CARBURETOR SHOULD DO 

While it is apparent that the chief function of a car- 
bureting device is to mix hydrocarbon vapors with air to 
secure mixtures that will burn, there are a number of fac- 
tors which must be considered before describing the prin- 
ciples of vaporizing devices. Almost any device which 
permits a current of air to pass over or through a vola- 
tile liquid will produce a gas which will explode when 



What a Carburetor Should Do 



115 



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116 Aviation Engines 

compressed and ignited in the motor cylinder. Modern 
carburetors are not only called upon to supply certain 
quantities of gas, but these must deliver a mixture to the 
cylinders that is accurately proportioned and which will 
be of proper composition at all engine speeds. 

Flexible control of the engine is sought by varying the 
engine speed by regulating the supply of gas to the cylin- 
ders. The power plant should run from its lowest to its 
highest speed without any irregularity in torque, i.e., the 
acceleration should be gradual rather than spasmodic. As 
the degree of compression will vary in value with the 
amount of throttle opening, the conditions necessary to 
obtain maximum power differ with varying engine speeds. 
When the throttle is barely opened the engine speed is 
low and the gas must be richer in fuel than when the 
throttle is wide open and the engine speed high. 

When an engine is turning over slowly the compression 
has low value and the conditions are not so favorable to 
rapid combustion as when the compression is high. At 
high engine speeds the gas velocity through the intake 
piping is higher than at low speeds, and regular engine 
action is not so apt to be disturbed by condensation of 
liquid fuel in the manifold due to excessively rich mixture 
or a superabundance of liquid in the stream of carbureted 
air. 

LIQUID FUEL. STORAGE AND SUPPLY 

The problem of gasoline storage and method of supply- 
ing the carburetor is one that is determined solely by 
design of the airplane. While the object of designers 
should be to supply the fuel to the carburetor by as simple 
means as possible the fuel supply system of some airplanes 
is quite complex. The first point to consider is the loca- 
tion of the gasoline tank. This depends upon the amount 
of fuel needed and the space available in the fuselage. 

A very simple and compact fuel supply system is shown 
at Fig. 41. In this instance the fuel container is placed 
immediately back of the engine cylinder. The carburetor 



Liquid Fuel Storage and Supply 117 

which is carried as indicated is joined to the tank by a 
short piece of copper or flexible rubber tubing. This is 
the simplest possible form of fuel supply system and one 
used on a number of excellent airplanes. 

As the sizes of engines increase and the power plant 
fuel consumption augments it is necessary to use more 
fuel, and to obtain a satisfactory flying radius without 
frequent landings for filling the fuel tank it is necessary 
to supply large containers. 

When a very powerful power plant is fitted, as on 
battle planes of high capacity, it is necessary to carry 
large quantities of gasoline. In order to use a tank of 
sufficiently large capacity it may be necessary to carry it 
lower than the carburetor. "When installed in this manner 
it is necessary to force fuel out of the tank by air pres- 
sure or to pump it with a vacuum tank because the gasoline 
tank is lower than the carburetor it supplies and the gaso- 
line cannot flow by gravity as in the simpler systems. 
While the pressure and gravity feed systems are generally 
used in airplanes, it may be well to describe the vacuum 
lift system which has been widely applied to motor cars 
and which may have some use in connection with airplanes 
as these machines are developed. 

STEWART VACUUM FUEL FEED 

One of the marked tendencies has been the adoption 
of a vacuum fuel feed system to draw the gasoline from 
tanks placed lower than the carburetor instead of using 
either exhaust gas or air pressure to achieve this end. The 
device generally fitted is the Stewart vacuum feed tank 
which is clearly shown in section at Fig. 42. In this sys- 
tem the suction of a motor is employed to draw gasoline 
from the main fuel tank to the auxiliary tank incorporated 
in the device and from this tank the liquid flows to the 
carburetor. It is claimed that all the advantages of the 
pressure system are obtained with very little more com- 
plication than is found on the ordinary gravity feed. The 
mechanism is all contained in the cylindrical tank shown, 



118 



Aviation Engines 



which may be mounted either on the front of the dash or 
on the side of the engine as shown. 

The tank is divided into two chambers, the upper one 
being the filling chamber and the lower one the emptying 



B ^-AirVent 

Atmospheric Valve, /s~~\\ 
Suction Valve x 
■From Gasoline 'Tank \ 



■Suction Pipe 



Drai 




Ca rburetor 



Plug-' 



To Carburetor 



F u el Ja n k 



Fig. 42. — The Stewart Vacuum Fuel Feed Tank. 



chamber. The former, which is at the top of the device, 
contains the float valve, as well as the pipes running to 
the main fuel container and to the intake manifold. The 
lower chamber is used to supply the carburetor with gaso- 
line and is under atmospheric pressure at all times, so the 
flow of fuel from it is by means of gravity only. Since 



Stewart Vacuum Feed System 119 

this chamber is located somewhat above the carburetor, 
there must always be free flow of fuel. Atmospheric pres- 
sure is maintained by the pipes A and B, the latter open- 
ing into the air. In order that the fuel will be sucked 
from a main tank to the upper chamber, the suction valve 
must be opened and the atmospheric valve closed. Under 
these conditions the float is at the bottom and the suction 
at the intake manifold produces a vacuum in the tank 
which draws the gasoline from the main tank to the upper 
chamber. When the upper chamber is filled at the proper 
height the float rises to the top, this closing the suction 
valve and opening the atmospheric valve. As the suction 
is now cut off, the lower chamber is filled by gravity owing 
to there being atmospheric pressure in both upper and 
lower chambers. A flap valve is provided between the 
two chambers to prevent the gasoline in the lower one 
from being sucked back into the upper one. The atmos- 
pheric and suction valves are controlled by the levers C 
and D, both of which are pivoted at E, their outer ends 
being connected by two coil springs. It is seen that the 
arrangement of these two springs is such that the float 
must be held at the extremity of its movement, and that 
it cannot assume an intermediate position. 

This intermittent action is required to insure that the 
upper part'of the tank may be under atmospheric pressure 
part of the time for the gasoline to flow to the lower cham- 
ber. When the level of gasoline drops to a certain point, 
the float falls, thus opening the suction valve and closing 
the atmospheric valve. The suction of the motor then 
causes a flow of fuel from the main container. As soon 
as the level rises to the proper height the float returns to 
its upper position. It takes about two seconds for the 
chamber to become full enough to raise the float, as but 
.05 gallon is transferred at a time. The pipe running from 
the bottom of the lower chamber to the carburetor extends 
up a ways, so that there is but little chance of dirt or water 
being carried to the float chamber. 

If the engine is allowed to stand long enough so that the 



120 Aviation Engines 

tank becomes empty, it will be replenished after the motor 
has been cranked over four or five times with the throttle 
closed. The installation of the Stewart Vacuum- Gravity 
System is very simple. The suction pipe is tapped into 
the manifold at a point as near the cylinders as possible, 
while the fuel pipe is inserted into the gasoline tank and 
runs to the bottom of that member. There is a screen at 
the end of the fuel pipe to prevent any trouble due to de- 
posits of sediment in the main container. As the fuel is 
sucked from the gasoline tank a small vent must be made 
in the tank filler cap so that the pressure in the main tank 
will always be that of the atmosphere. 

EARLY VAPORIZER FORMS 

The early types of carbureting devices were very crude 
and cumbersome, and the mixture of gasoline vapor and 
air was accomplished in three ways. The air stream was 
passed over the surface of the liquid itself, through loosely 
placed absorbent material saturated with liquid, or directly 
through the fuel. The first type is known as the surface 
carburetor and is now practically obsolete. The second 
form is called the "wick" carburetor because the air 
stream was passed over or through saturated wicking. The 
third form was known as a "bubbling" carburetor. While 
these primitive forms gave fairly good results with the 
early slow-speed engines and the high grade, or very 
volatile, gasoline which was first used for fuel, they would 
be entirely unsuitable for present forms of engines be- 
cause they would not carburate the lower grades of gaso- 
line which are used to-day, and would not supply the 
modern high-speed engines with gas of the proper consis- 
tency fast enough even if they did not have to use very 
volatile gasoline. The form of carburetor used at the 
present time operates on a different principle. These 
devices are known as "spraying carburetors." The fuel 
is reduced to a spray by the suction effect of the entering 
air stream drawing it through a fine opening. 

The advantage of this construction is that a more 



Early Vaporizer Forma 



121 



thorough amalgamation of the gasoline and air particles 
is obtained. With the earlier types previously considered 
the air would combine with only the more volatile elements, 
leaving the heavier constituents in the tank. As the fuel 
became stale it was difficult to vaporize it, and it had to 



Jump Value 
Adjustment 



Mixture 
Passage 




Entrance 



Gasoline Adjustment 



Fig. 43. — Marine-Type Mixing Valve, by -which Gasoline is Sprayed into Air 
Stream Through Small Opening in Air-Valve Seat. 



be drained off and fresh fuel provided before the proper 
mixture would be produced. It will be evident that when 
the fuel is sprayed into the air stream, all the fuel will be 
used up and the heavier portions of the gasoline will be 
taken into the cylinder and vaporized just as well as the 
more volatile vapors. 

The simplest form of spray carburetor is that shown 
at Fig. 43. In this the gasoline opening through which 



122 Aviation Engines 

the fuel is sprayed into the entering air stream is closed 
by the spring-controlled mushroom valve which regulates 
the main air opening as well. When the engine draws in 
a charge of air it unseats the valve and at the same time 
the air flowing around it is saturated with gasoline par- 
ticles through the gasoline opening. The mixture thus 
formed goes to the engine through the mixture passage. 
Two methods of varying the fuel proportions are provided. 
One of these consists of a needle valve to regulate the 
amount of gasoline, the other is a knurled screw which 
controls the amount of air by limiting the lift of the 
jump valve. 

DEVELOPMENT OF FLOAT-FEED CARBURETOR 

The modern form of spraying carburetor is provided 
with two chambers, one a mixing chamber through which 
the air stream passes and mixes with a gasoline spray, 
the other a float chamber in which a constant level of fuel 
is maintained by simple mechanism. A jet or standpipe 
is used in the mixing chamber to spray the fuel through 
and the object of the float is to maintain the fuel level 
to such a point that it will not overflow the jet when the 
motor is not drawing in a charge of gas. With the simple 
forms of generator valve in which the gasoline opening is 
controlled by the air valve, a leak anywhere in either 
valve or valve seat will allow the gasoline to flow continu- 
ously whether the engine is drawing in a charge or not. 
The liquid fuel collects around the air opening, and when 
the engine inspires a charge it is saturated with gasoline 
globules and is excessively rich. With a float-feed con- 
struction, which maintains a constant level of gasoline at 
the right height in the standpipe, liquid fuel will only be 
supplied when drawn out of the jet by the suction effect 
of the entering air stream. 



The first form of spraying carburetor ever applied 
successfully was evolved by Maybach for use on one of the 



Maybaclis Early Design 



12S 




124 Aviation Engines 

earliest Daimler engines. The general principles of opera- 
tion of this pioneer float-feed carburetor are shown at 
Fig. 44, A. The mixing chamber and valve chamber were 
one and the standpipe or jet protruded into the mixing 
chamber. It was connected to the float compartment by a 
pipe. The fuel from the tank entered the top of the float 
compartment and the opening was closed by a needle 
valve carried on top of a hollow metal float. When the 
level of gasoline in the float chamber was lowered the 
float would fall and the needle valve uncover the opening. 
This would permit the gasoline from the tank to flow into 
the float chamber, and as the chamber filled the float would 
rise until the proper level had been reached, under which 
conditions the float would shut off the gasoline opening. 
On every suction stroke of the engine the inlet valve, which 
was an automatic type, would leave its seat and a stream 
of air would be drawn through the air opening and around 
the standpipe or jet. This would cause the gasoline to 
spray out of the tube and mix with the entering air stream. 
The form shown at B was a modification of Maybach's 
simple device and was first used on the Phoenix-Daimler 
engines. Several improvements are noted in this device. 
First, the carburetor was made one unit by casting the 
float and mixing chambers together instead of making them 
separate and joining them by a pipe, as shown at A. The 
float construction was improved and the gasoline shut-off 
valve was operated through leverage instead of being di- 
rectly fastened to the float. The spray nozzle was sur- 
rounded by a choke tube which concentrated the air stream 
around it and made for more rapid air flow at low engine 
speeds. A conical piece was placed over the jet to break 
up the entering spray into a mist and insure more intimate 
admixture of air and gasoline. The air opening was 
provided with an air cone which had a shutter controlling 
the opening so that the amount of air entering could be 
regulated and thus vary the mixture proportions within 
certain limits. 



Schebler Carburetor Construction 125 

COKCEITTRIC FLOAT AND JET TYPE 

The form shown at B has been further improved, and 
the type shown at C is representative of modern single 
jet practice. In this the float chamber and mixing chamber 
are concentric. A balanced float mechanism which insures 
steadiness of feed is used, the gasoline jet or standpipe 
is provided with a needle valve to vary the amount of 
gasoline supplied the mixture and two air openings are 
provided. The main air port is at the bottom of the 
vaporizer, while an auxiliary air inlet is provided at the 
side of the mixing chamber. There are two methods of 
controlling the mixture proportions in this form of car- 
buretor. One may regulate the gasoline needle or adjust 
the auxiliary air valve. 

SCHEBLER CARBURETOR 

A Schebler carburetor^ which has been used on some 
airplane engines, is shown in Fig. 45. It will be noticed 
that a metering pin or needle valve opens the jet when 
the air valve opens. The long arm of a leverage is con- 
nected to the air valve, while the short arm is connected 
to the needle, the reduction in leverage being such that 
the needle valve is made to travel much less than the air 
valve. For setting the amount of fuel passed or the size 
of the jet orifice when running with the air valve closed, 
there is a screw which raises or lowers the fulcrum of 
the lever and there is also a dash control having the same 
effect by pushing down the fulcrum against a small spring. 
A long extension is given to the venturi tube which is very 
narrow around the jet orifices, which are horizontal and 
shown at A in the drawing. Fuel enters the float chamber 
through the union M, and the spring P holds the metering 
pin upward against the restraining action of the lever. 
The air valve may be set by an easily adjustable knurled 
screw shown in the drawing, and fluttering of the valve is 
prevented by the piston dash pot carried in a chamber 
above the valve into which the valve stem projects. The 



126 



Aviation Engines 




Claudel Carburetor 



127 



primary air enters beneath the jet passage and there is 
a small throttle in the intake to increase the speed of air 
flow for starting purposes. The carburetor is adapted for 
the use of a hot-air connection to the stove around the 
exhaust pipe and it is recommended that such a fitting be 
supplied. The lever which controls the supply of air 



,' Mixture Outlet 



float Valve % 



Float 

Bowl -H 



--Throttle 



^-Mixing 

Chamber. 




Filter 

Screen' 



-Compound 
Spray Nozzle 



><--•■ Fuel Intake 



Fig. 46. — The Claudel Carburetor 



through the primary air intake is so arranged that if 
desired it can be connected with a linkage on the dash 
or control column by means of a flexible wire. 

THE CLAUDEL ( FRENCH) CARBURETOR 

This carburetor is of extremely simple construction, 
because it has no supplementary or auxiliary air valve 
and no moving parts except the throttle controlling the 
gas flow. The construction is already shown in Fig. 46. 



128 Aviation Engines 

The spray jet is eccentric with a surrounding sleeve or 
tube in which there are two series of small orifices, one 
at the top and the other near the bottom. The former 
are about level with the spray jet opening. The sleeve 
surrounding the nozzle is closed at the top. The air, 
passing the upper holes* in the sleeve, produces a vacuum 
in the sleeve, thereby drawing air in through the bottom 
holes. It is this moving interior column of air that con- 
trols the flow of gasoline from the nozzle. Owing to the 
friction of the small passages, the speed of air flow through 
the sleeve does not increase as fast as the speed of air 
flow outside the sleeve, hence there is a tendency for the 
mixture to remain constant. The throttle of this carbure- 
tor is of the barrel type, and the top of the spray nozzle 
and its surrounding sleeve are located inside the throttle. 

STEWART METERING PIN CARBURETOR 

The carburetor shown at Fig. 47 is a metering type in 
which the vacuum at the jet is controlled by the weight 
of the metering valve surrounding the upright metering 
pin. The only moving part is the metering valve, which 
rises and falls with the changes in vacuum. The air 
chamber surrounds the metering valve, and there is a mix- 
ing chamber above. As the valve is drawn up the gasoline 
passage is enlarged on account of the predetermined taper 
on the metering pin, and the air passage also is increased 
proportionately, giving the correct mixture. A dashpot 
at the bottom of the valve checks flutter. In idling the 
valve rests on its seat, practically closing the air and giv- 
ing the necessary idling mixture. A passage through the 
valve acts as an aspirating tube. When the valve is closed 
altogether the primary air passes through ducts in the 
valve itself, giving the proper amount for idling. The 
one adjustment consists in raising or lowering the tapered 
metering pin, increasing or decreasing the supply of 
gasoline. Dash control is supplied. This pulls down the 
metering pin, increasing the gasoline flow. The duplex 
type for eight- and twelve-cylinder motors is the same in 



Multiple Nozzle Vaporizers 



129 



principle as model 25, but it is a double carburetor syn- 
chronized as to throttle movements, adjustments, etc. The 
duplex for aeronautical motors is made of cast aluminum 
alloy. 

MULTIPLE NOZZLE VAPORIZERS 

To secure properly proportioned mixtures some car- 
buretor designers have evolved forms in which two or 
more nozzles are used in a common mixing chamber. The 
usual construction is to use two, one having a small open- 
ing and placed in a small air tube and used only for low 



Throttle 



Automatic 
Metering Valve ..., 



Aspirating. 
Tube 



.-Primarf 
Air Passages 



Dash Pot- 



Tapered 
Metering Pin- 




Flared End of 
Aspirating Tube, 




"■ Inlet Needle Valve H || 

' * -Gasoline Strainer ' 




^Mixing Chamber 



Automatic^ 
.Metering Valve 

Automatic 
Metering Valve 



Air Chamber 



Throttle. 



/Primary Air 

Passage 



- Gasoline 



^Tapered 
Metering 
Pin 



Aspiranf Tube-'' 
Dash Pot-''' 

Tapered 
Metering Pin'' 




•Inlet Needle 
Valve 



^'Gasoline '• 
Strainer 



'Gasoline Passage 



Fig. 47. — The Stewart Metering Pin Carburetor. 



130 Aviation Engines 

speeds, the other being placed in a larger air tube and 
having a slightly augmented bore so that it is employed 
on intermediate speeds. At high speeds both jets would 
be used in series. Some multiple jet carburetors could 
be considered as a series of these instruments, each one 
being designed for certain conditions of engine action. 
They would vary from small size just sufficient to run 
the engine at low speed to others having sufficient capacity 
to furnish gas for the highest possible engine speed when 
used in conjunction with the smaller members which have 
been brought into service progressively as the engine speed 
has been augmented. The multiple nozzle carburetor dif- 
fers from that in which a single spray tube is used only 
in the construction of the mixing chamber, as a common 
float bowl can be used to supply all spray pipes. It is 
common practice to bring the jets into action progres- 
sively by some form of mechanical connection with the 
throttle or by automatic valves.' 

The object of any multiple nozzle carburetor is to 
secure greater flexibility and endeavor to supply mix- 
tures of proper proportions at all speeds of the engine. 
It should be stated, however, that while devices of this 
nature lend themselves readily to practical application it 
is more difficult to adjust them than the simpler forms 
having but one nozzle. When a number of jets are used 
the liability of clogging up the carburetor is increased, 
and if one or more of the nozzles is choked by a particle 
of dirt or water the resulting mixture trouble is difficult 
to detect, One of the nozzles may supply enough gasoline 
to permit the engine to run well at certain speeds and yet 
not be adequate to supply the proper amount of gas under 
other conditions. In adjusting a multiple jet carburetor 
in which the jets are provided with gasoline regulating 
needles, it is customary to consider each nozzle as a dis- 
tinct carburetor and to regulate it to secure the best motor 
action at that throttle position which corresponds to the 
conditions under which the jet is brought into service. 
For instance, that supplied the primary mixing chamber 



Ball and Ball Two-Stage Carburetor 



131 



should be regulated with the throttle partly closed, while 
the auxiliary jet should be adjusted with the throttle fully 
opened. 

BALL. AXD BALL TWO-STAGE CARBURETOR 

This is a two-stage vaporizing device, hot air being 
used in the primary or initial stage of vaporization and 
cold air in the supplementary stage. Eeferring to the 
sectional illustration at Fig. 48, it will be seen that there 




Fig. 48. — The BaU and Ball Two-Stage Carburetor. 



is a hot-air passage with a choke-valve ; the primary ven- 
turi appears at B ; J is its gasoline jet, and V is a spring- 
loaded idling valve in a fixed air opening. These parts 
constitute the primary system. In the secondary system 
A is a cold-air passage, T a butterfly valve and J a gaso- 
line jet discharging into the cold-air passage. This sys- 
tem is brought into operation by opening the butterfly T. 
A connection between the butterfly T and the throttle, not 
shown, throw T s the butterfly wide open w T hen the throttle 
is not quite wide open; at all other times the butterfly 



132 Aviation Engines 

is held closed by a spring. The cylindrical chamber at 
the right of the mixing chamber has an extension E of 
reduced diameter connecting it with the intake manifold 
through a passage D. A restricted opening connects the 
float chamber with the cylindrical chamber so that the 
gasoline level is the same in both. A loosely fitting plun- 
ger P in the cylindrical chamber has an upward extension 
into the small part of the chamber. is a small air 
opening and M is a passage from the cylindrical chamber 
to the mixing chamber. Air constantly passes through 
this when the carburetor is in operation. The carburetor 
is really two in one. The primary carburetor is made up 
of a central jet in a venturi passage. The float chamber 
is eccentric. In the air passage there is a fixed opening, 
and additional air is taken in by the opening through 
suction of a spring-opposed air valve. The second stage, 
which comes into play as soon as the carburetor is called 
upon for additional mixture above low medium speeds, 
is made up of an independent air passage containing an- 
other air valve. As the valve is opened this jet is un- 
covered, and air is led past it. For easy starting an 
extra passage leads from the float bowl passage to a point 
above the throttle. All the suction falls upon this passage 
when the throttle is closed. The passage contains a plun- 
ger and acts as a pick-up device. When the vacuum in- 
creases the plunger rises and shuts off the flow of gasoline 
from the intake passage. As the throttle is opened the 
vacuum in the intake passage is broken, and the plunger 
falls, causing gasoline to gather above it. This is imme- 
diately drawn through the pick-up passage and gives the 
desired mixture for acceleration. 

MASTER MULTIPLE-JET CARBURETOR 

This carburetor, shown in detail in Figs. 49 and 50, 
has been very popular in racing cars and aviation engines 
because of exceptionally good pick-up qualities and its 
thorough atomization of fuel. Its principle of operation 
is the breaking up of the fuel by a series of jets, which 



Master Multiple-Jet Carburetor 



133 



vary in number from fourteen to twenty- one, according 
to the size of the carburetor. These are uncovered by 
opening the throttle, which is curved — a patented feature 
— to secure the correct progression of jets. The carbu- 



S A £ Standard Flange 




14 to 19 Fine Holes 
Where Fuel Comes 
Out of Distributer 
as Throttle is Opened 



Air 
intake 



Where Fuel Enters Distributer 
First Being Thoroughly Filtered 



Y — Normal Running: 
Economy Position 





Fig. 49. — The Master Carburetor. 



retor has an eccentric float chamber, from which the gas- 
oline is led to the jet piece from which the jets stand up 
in a row. The tops of these jets are closed until the 
throttle is opened far enough to pass them, which it does 
progressively. The air opening is at the bottom, and the 
throttle opening is such that a modified venturi is formed. 



134 



Aviation Engines 



The throttle is carried in a cylindrical barrel with the jets 
placed below it, and the passage from the barrel to the 
intake is arranged so that there is no interruption in the 
flow. For easy starting a dash-controlled shutter closes 



Rotary 

Throttle. 




Fig. 50. — Sectional View of Master Carburetor Showing Parts. 

off the air, throwing the suction on the jets, thus giving 
a rich mixture. 

The only adjustment is for idling, and once that is 
fixed it need never be touched. This is in the form of 
a screw and regulates the position of the throttle when 
at idling position. The dash control has high-speed, nor- 
mal and rich-starting positions. In installing the Master 
carburetor the float chamber may be turned either toward 
the radiator or driver's seat. If the float is turned toward 
the radiator, however, a forward lug plate should be 
ordered ; otherwise it will be difficult to install the control. 
The throttle lever must go all the way to the stop lug 



Compound Nozzle Zenith Carburetor 



135 



or maximum power will not be secured. In adjusting the 
idle screw it is turned in for rich and out for lean. 

COMPOUND NOZZLE ZENITH CARBURETOR 

The Zenith carburetor, shown at Fig. 51, has become 
very popular for airplane engine use because of its sim- 
plicity, as mixture compensation is secured by a compen- 
sating compound nozzle principle that works very well in 
practice. To illustrate this principle briefly, let us con- 
sider the elementary type of carburetor or mixing valve, 
as shown in Fig. 52, A. It consists of a single jet or 
spraying nozzle placed in the path of the incoming air 
and fed from the usual float chamber. It is a natural 



PRIMING HOLE U 



PRIMING TUBE J 

REGULATING 
SCREW O 




BUTTERFLY T 



SECONDARY 
WELL P 



CHOKE X 



CAP JET H 



MAIN JET 



COMPENSATOR I 



Fig. 51. — Sectional View of Zenith Compound Nozzle Compensating 

Carburetor. 



136 



Aviation Engines 




Action of Zenith Carburetor 137 

inference to suppose that as the speed of the motor in- 
creases, both the flow of air and of gasoline will increase 
in the same proportion. Unhappily, snch is not the case. 
There is a law of liquid bodies which states that the flow 
of gasoline from the jet increases under suction faster 
than the flow of air, giving a mixture which grows richer 
and richer — a mixture containing a much higher percent- 
age of gasoline at high suction than at low. The tendency 
is shown by the accompanying curve (Fig. 52, B), which 
gives the ratio of gasoline to air at varying speeds from 
this type of jet. The mixture is practically constant only 
between narrow limits and at very high speed. The most 
common method of correcting this defect is by putting 
various auxiliary air valves which, adding air, tends to 
dilute this mixture as it gets too rich. It is difficult with 
makeshift ' devices to gauge this dilution accurately for 
every motor speed. 

Now, if we have a jet which grows richer as the suction 
increases, the opposite type of jet is one which would 
grow leaner under similar conditions. Baverey, the in- 
ventor of the Zenith, discovered the principle of the con- 
stant flow device which is shown in Fig. 52, C. Here 
a certain fixed amount of gasoline determined by the open- 
ing I is permitted to flow by gravity into the well J open 
to the air. The suction at jet H has no effect upon the 
gravity compensator I because the suction is destroyed 
by the open well J. The compensator, then, delivers a 
steady rate of flow per unit of time, and as the motor 
suction increases more air is drawn up, while the amount 
of gasoline remains the same and the mixture grows 
poorer and poorer. Fig. 52, D, shows this curve. 

By combining these two types of rich and poor mixture 
carburetors the Zenith compound nozzle was evolved. In 
Fig. 52, E, we have both the direct suction or richer type 
leading through pipe E and nozzle G and the " constant 
flow" device of Baverey shown at J, I, K and nozzle H. 
One counteracts the defects of the other, so that from 
the cranking of the motor to its highest speed there is 



138 



Aviation Engines 



a constant ratio of air and gasoline to supply efficient 
combustion. 

In addition to the compound nozzle the Zenith is 
equipped with a starting and idling well, shown in the 
cut of Model L carburetor at P and J. This terminates 
in a priming hole at the edge of the butterfly valve, 
where the suction is greatest when this valve is slightly 
open. The gasoline is drawn up by the suction at the 
priming hole and, mixed with the air rushing by the but- 
terfly, gives an ideal slow speed mixture. At higher speeds 



Mixing 

Chambers-' 



Floai 3owh s 
Cover \ 



Float 

Bowl -> 



Fuel Inlet 




~-Thro-H-le Discs 



ThroH/e 
Lever 



.-Air Intake 



Fig. 53. — The Zenith Duplex Carburetor for Airplane Motors of the V Type. 

with the butterfly valve opened further the priming well 
ceases to operate and the compound nozzle drains the well 
and compensates correctly for any motor speed. 

With the coming of the double motor containing eight 
or twelve cylinders arranged in two V blocks, the question 
of good carburetion has been a problem requiring much 
study. The single carburetor has given only indifferent 
results due to the strong cross suction in the inlet mani- 
fold from one set of cylinders to the other. This natur- 
ally led to the adoption of two carburetors in which each 
set of cylinders was independently fed by a separate car- 



Zenith Carburetor Installation 



139 



buretor. Kesults from this system were very good when 
the two carburetors were working exactly in unison, but 
as it was extremely difficult to accomplish this co-opera- 
tion, especially where the adjustable type was employed, 







.Intake Pipe 


A i r j^v^r^f" /ffl^? 
Stove (?j& / ?*3%&* "wSfc^k 




Bit iKS^)^ •wtf^^Jk^ 


\^~ ~~~^m^3^SKB*m^^^i&sJti 




In MESf WT\ • • 






If j «f \ 


Centrifugal TB0L-- -~ ~~~~~~~~~w$k 
Water Pump — i^k fte*§ 


Lt'«i 


> - *3*%i-. jar Air Stove 1 
tFMhfiP- f Surrounding i 
\JBmf W Exhaust Pipes 1 


Flexible ^^^^^^ / 1 
Air P'\pe~^"^ T&74L ' 


m\l 


R\?~ p Water Pi pes 
W| jfijf to Jacket 


Jacketed Manifold' ik 
or Y Branch 


^n^i^S 


5jdF&pr Flexible 
Jr Air Pipe 

i .-Zenith Duplex 
F^^ Carb'uretor 


; 







Fig. 54. — Rear View of Curtiss 0X2 90 Horse-Power Airplane Motor 
Showing Carburetor Location and Hot Air Leads. 

this system never gained in favor. The next logical step 
was the Zenith Duplex, shown at Fig. 53. This consists 
of two separate and distinct carburetors joined together 
so that a common gasoline float chamber and air inlet 
could be used by both. It does away with cross suction 
in the manifold because each set of cylinders has a sep- 



140 Aviation Engines 

arate intake of its own. It does away with two carburet- 
ors and makes for simplicity. The practical application 
of the Zenith carburetor to the Curtiss 90 horse-power 
0X2 motor used on the J.N.4 standard training machine 
is shown at Fig. 54, which outlines a rear view of the 
engine in question. The carburetor is carried low to per- 
mit of fuel supply from a gravity tank carried back of 
the motor. 

UTILITY OF GASOLINE STRAINERS 

Many carburetors include a filtering screen at the point 
where the liquid enters the float chamber in order to keep 
dirt or any other foreign matter which may be present 
in the fuel from entering the float chamber. This is not 
general practice, however, and the majority of vaporizers 
do not include a filter in their construction. It is very 
desirable that the dirt should be kept out of the carbu- 
retor because it may get under the float control fuel valve 
and cause flooding by keeping it raised from its seat. If 
it finds its way into the spray nozzle it may block the 
opening so that no gasoline will issue or may so constrict 
the passage that only very small quantities of fuel will 
be supplied the mixture. Where the carburetor itself is 
not provided with a filtering screen a simple filter is 
usually installed in the pipe line between the gasoline 
tank and the float chamber. 

Some simple forms of filters and separators are shown 
at Fig. 55. That at A consists of a simple brass casting 
having a readily detachable gauze screen and a settling 
chamber of sufficient capacity to allow the foreign matter 
to settle to the bottom, from which it is drained out by 
a pet cock. Any water or dirt in the gasoline will settle 
to the bottom of the chamber, and as all fuel delivered 
to the carburetor must pass through the wire gauze screen 
it is not likely to contain impurities when it reaches the 
float chamber. The heavier particles, such as scale from 
the tank or dirt and even water, all of which have greater 
weight than the gasoline, will sink to the bottom of the 



Utility of Gasoline Strainers 



141 



chamber, whereas light particles, such as lint, will be pre- 
vented from flowing into the carburetor by the filtering 
screen. 

The filtering device shown at B is a larger appliance 
than that shown at A, and should be more efficient as a 



Supporting Boss 




Gasoline 
from Tank 



To Carburetor 



Jo Carburetor 

Wire Gauze 

ire Gauze 

Settling Chamber' 
Settling Chamber 




B 



Supporting Lug 

\ 

SS3 



Gasoline 
from. Tank 



Gasoline Tank 




To Carburetor 



Wire Gauze \ 

To Carburetor^ 

Settling Chamber 

Settling Chamber 




Fig. 55. — Types of Strainers Interposed Between Vaporizer and Gasoline 
Tank to Prevent Water or Dirt Passing Into Carbureting Device. 

separator because the gasoline is forced to pass through 
three filtering screens before it reaches the carburetor. 
The gasoline enters the device shown at C through a bent 
pipe which leads directly to the settling chamber and 
from thence through a wire gauze screen to the upper 
compartment which leads to the carburetor. The device 
shown at D is a combination strainer, drain, and sedi- 



142 Aviation Engines 

ment cup. The filtering screen is held in place by a 
spring and both are removed by taking out a plug at the 
bottom of the device. The shut-ofT valve at the top of 
the device is interposed between the sediment cup and 
the carburetor. This separating device is incorporated 
with the gasoline tank and forms an integral part of the 
gasoline supply system. The other types shown are de- 
signed to be interposed between the gasoline tank and 
the carburetor at any point in the pipe line where they 
may be conveniently placed. 

INTAKE MANIFOLD DESIGN AND CONSTRUCTION 

On four- and six-cylinder engines and in fact on all 
multiple-cylinder forms, it is important that the piping 
leading from the carburetor to the cylinders be made in 
such a way that the various cylinders will receive their 
full quota of gas and that each cylinder will receive its 
charge at about the same point in the cycle of operations. 
In order to make the passages direct the bends should 
be as few as possible, and when curves are necessary they 
should be of large radius because an abrupt corner will not 
only impede gas flow but will tend to promote condensation 
of the fuel. Every precaution should be taken with four- 
and six-cylinder engines to insure equitable gas distri- 
bution to the valve chambers if regular action of the 
power plant is desired. If the gas pipe has many turns 
and angles it will be difficult to charge all cylinders prop- 
erly. On some six-cylinder aviation engines, two carbu- 
retors are used because of trouble experienced with man- 
ifolds designed for one carburetor. Duplex carburetors 
are necessary to secure the best results from eight- and 
twelve-cylinder V engines. 

The problem of intake piping is simplified to some 
extent on block motors where the intake passage is cored 
in the cylinder casting and where but one short pipe is 
needed to join this passage to the carburetor. If the 
cylinders are cast in pairs a simple pipe of T or Y form 
can be used with success. When the engine is of a type 



Intake Manifold Construction 143 

using individual cylinder castings, especially in the six- 
cylinder power plants, the proper application and instal- 
lation of suitable piping is a difficult problem. The reader 
is referred to the various engine designs outlined to as- 
certain how the inlet piping has been arranged on repre- 
sentative aviation engines. Intake piping is constructed 
in two ways, the most common method being to cast the 
manifold of brass or aluminum. The other method, which 
is more costly, is to use a built-up construction of copper 
or brass tubing with cast metal elbows and Y pieces. One 
of the disadvantages advanced against the cast manifold 
is that blowholes may exist which produce imperfect cast- 
ings and which will cause mixture troubles because the 
entering gas from the carburetor, which may be of proper 
proportions, is diluted by the excess air which leaks in 
through the porous casting. Another factor of some mo- 
ment is that the roughness of the walls has a certain 
amount of friction which tends to reduce the velocity of 
the gases, and when projecting pieces are present, such 
as core wire or other points of metal, these tend to collect 
the drops of liquid fuel and thus promote condensation. 
The advantage of the built-up construction is that the 
walls of the tubing are very smooth, and as the castings 
are small it is not difficult to clean them out thoroughly 
before they are incorporated in the manifold. The tubing 
and castings are joined together by hard soldering, braz- 
ing or autogenous welding. 

COMPENSATING FOR VARYING ATMOSPHERIC CONDITIONS 

The low-grade gasoline used at the present time makes 
it necessary to use vaporizers that are more susceptible 
to atmospheric variations than when higher grade and 
more volatile liquids are vaporized. Sudden temperature 
changes, sometimes being as much as forty degrees rise 
or fall in twelve hours, affect the mixture proportions to 
some extent, and not only changes in temperature but 
variations in altitude also have a bearing on mixture pro- 
portions by affecting both gasoline and air. As the tern- 



144 



Aviation Engines 



perature falls the specific gravity of the gasoline increases 
and it becomes heavier, this producing difficulty in vapor- 
izing. The tendency of very cold air is to condense gas- 
oline instead of vaporizing it and therefore it is necessary 
to supply heated air to some carburetors to obtain proper 
mixtures during cold weather. In order that the gas mix- 
tures will ignite properly the fuel must be vaporized and 
thoroughly mixed with the entering air either by heat or 





4 9 

& 

&I0 

10 

-O 

k. 
D 
lO 
«5 
<D 

V 

£13 

w 
O 

£ 
< 14 

15 

( 


























i 


























































































































) 2000 4000 6000 8000 10.0 
Al+itude in Feet Above Sea Level 


00 



Fig. 56. — Chart Showing Diminution of Air Pressure as Altitude Increases. 

high velocity of the gases. The application of air stoves 
to the Curtiss OX2 motor is clearly shown at Fig. 54. It 
will be seen that flexible metal pipes are used to convey 
the heated air to the air intakes of the duplex mixing 
chamber. 

HOW HIGH ALTITUDE AFFECTS POWER 

Any internal combustion engine will show less power 
at high altitudes than it will deliver at sea level, and this 
has caused a great deal of questioning. " There is a good 



How High Altitude Affects Power 145 

reason for this," says a writer in "Motor Age," "and 
it is a physical impossibility for the engine to do other- 
wise. The difference is dne to the lower atmospheric 
pressure the higher np we get. That is, at sea level the 
atmosphere has a pressure of 14.7 pounds per square inch ; 
at 5,000 feet above sea level the pressure is approximately 
12.13 pounds per square inch, and at 10,000 feet it is 10 
pounds per square inch. From this it will be seen that 
the final pressure attained after the piston has driven 
the gas into compressed condition ready for firing is lower 
as the atmospheric pressure drops. This means that there 
is not so much power in the compressed charge of gas the 
higher up you get above sea level. 

"For example, suppose the compression ratio to be 
4:^2 to 1; in other words, suppose the air space above the 
piston to have 4*^ times the volume when the piston is 
at the bottom of its stroke that it has when the piston is 
at the top of the stroke. That is a common compression 
ratio for an average motor, and is chosen because it is 
considered to be the best for maximum horse-power and 
in order that the compression pressure will not be so high 
as to cause pre-ignition. Knowing the compression ratio, 
we can determine the final pressure immediately before 
ignition by substituting in the standard formula: 



" - " (?) 



1.3 



in which P is the atmospheric pressure; P 1 is the final 

V 

pressure, and — is the compression ratio, therefore P 1 = 
V 1 

14.7 (4.5) 1 ' 3 = 104 pounds per square inch, absolute. 

"That is, 104 pounds per square inch is the most effi- 
cient final compression pressure to have for this engine 
at sea level, since it comes directly from the compression 
ratio. 

"Now supposing we consider that the altitude is 7,000 



146 Aviation Engines 

feet above sea level. At this height the atmospheric press- 
ure is 11.25 pounds per square inch, approximately. In 
this case we can again substitute in the formula, using 
the new atmospheric pressure figure. The equation be- 
comes : 

P 1 =11.25 (4.5) 13 — 79.4 pounds per square inch, ab- 
solute. 

"Therefore we now have a final compression pressure 
of only 79.4 pounds per square inch, which is considerably 
below the pressure we have just found to be the most 
efficient for the motor. The resulting power drop is evi- 
dent. 

"It should be borne in mind that these final compres- 
sion pressures are absolute pressures — that is, they in- 
clude the atmospheric pressure. In the first case, to get 
the pressure above atmospheric you would subtract 14.7 
and in the latter 11.25 would have to be deducted. In 
other words, where the sea level compression is 89.3 pounds 
per square inch above the atmosphere, the same motor 
will have only a compression pressure of 68.15 pounds 
per square inch above the atmosphere at 7,000 feet ele- 
vation. 

"From the above it is evident that in order to bring 
the final compression pressure up to the efficient figure 
we have determined, a different compression ratio would 
have to be used. That is, the final volume would have 
to be less, and as it is impossible to vary this to meet 
the conditions of altitude, the loss of power cannot be 
helped except by the replacing of the standard pistons 
with some that are longer above the wrist-pin so as to 
reduce the space above the pistons when on top center. 
Then if the ratio is thereby raised to some such figures 
as 5 to 1, the engine will again have its proper final press- 
ure, but it will still not have as much power as it would 
have at sea level, since the horse-power varies directly 
with the atmospheric pressure, final compression being 
kept constant. That is, at 7,000 feet the horse-power of 



The Diesel System 147 

an engine that had 40 horse-power at sea level would be 
equal to 

11.25 

' = 30 . 6 horse-power. 

14.7 

"If the original compression ratio of 4.5 were retained, 
the drop in horse-power would be even greater than this. 
These computations and remarks will make it clear that 
the designer who contemplates building an airplane for 
high altitude use should see to it that it is of sufficient 
power to compensate for the drop that is inevitable when 
it is up in the air. This is often illustrated in stationary 
gas-engine installations. An engine that had a sea-level 
rating amply sufficient for the work required, might not 
be powerful enough when brought up several thousand 
feet." When one considers that airplanes attain heights 
of over 18,000 feet, it will be evident that an ample mar- 
gin of engine power is necessary. 

THE DIESEL SYSTEM 

A system of fuel supply developed by the late Dr. 
Diesel, a German chemist and engineer, is attracting con- 
siderable attention at the present time on account of the 
ability of the Diesel engine to burn low-grade fuels, such 
as crude petroleum. In this system the engines are built 
so that very high compressions are used, and only pure 
air is taken into the cylinder on the induction stroke. 
This is compressed to a pressure of about 500 pounds 
per square inch, and sufficient heat is produced by this 
compression to explode a hydrocarbon mixture. As the 
air which is compressed to this high point cannot burn, 
the fuel is introduced into the cylinder combustion cham- 
ber under still higher compression than that of the com- 
pressed air, and as it is injected in a fine stream it is 
immediately vaporized because of the heat. Just as soon 
as the compressed air becomes thoroughly saturated with 
the liquid fuel, it will explode on account of the degree of 



148 Aviation Engines 

heat present in the combustion chamber. Such motors 
have been used in marine and stationary applications, but 
are not practical for airplanes or motor cars because of 
lack of flexibility and great weight in proportion to power 
developed. The Diesel engine is the standard power plant 
used in submarine boats and motor ships, as its efficiency 
renders it particularly well adapted for large units. 

NOTES ON CARBURETOR INSTALLATION IN AIRPLANES 

A writer in "The Aeroplane, " an English publication, 
discourses on some features of carburetor installation that 
may be of interest to the aviation student, so portions of 
the dissertation are reproduced herewith. 

''Users of airplanes fitted with ordinary type carburetors will 
do well to note carefully the way in which these are fitted, for 
several costly machines have been burnt lately through the sheer 
carelessness of their users. These particular machines were fitted 
with a high powered V-type engine, made by a firm which is 
famous as manufacturers of automobiles de luxe. In these engines 
there are four carburetors, mounted in the V between the cylinders. 
"When the engine is fitted as a tractor, the float chambers are in 
front of the jet chambers. Consequently, when the tail of the 
machine is resting on the ground, the jets are lower than the level 
of the gasoline in the float chamber. 

"Quite naturally, the gasoline runs out of the jet, if it is left 
turned on when the machine is standing in its normal position, 
and trickles into the V at the top of the crank-case. Thence it 
runs down to the tail of the engine, where the magnetos are fitted, 
and saturates them. If left long enough, the gasoline manages 
to soak well into the fuselage before evaporating. And what does 
evaporate makes an inflammable gas in the forward cockpit. Then 
some one comes along and starts up the engine. The spark-gap 
of the magneto gives one flash, and the whole front of the machine 
proceeds to give a Fourth of July performance forthwith. Natu- 
rally, one safeguard is to turn the petrol off directly the machine 
lands. Another is never to turn it on till the engine is actually 
being started up. 

"One would be asking too much of the human boy — who is 
officially regarded as the only person fit to fly an aeroplane — if 
one depended upon his memory of such a detail to save his ma- 
chine, though one might perhaps reasonably expect the older pilots 
to remember not to forget. Even so, other means of prevention 



Notes on Carburetor Installation 149 

are preferable, for fire is quite as likely to occur from just the 
same cause if the engine happens to be a trifle obstinate in start- 
ing, and so gives the carburetors several minutes in which to drip 
— in which operation they would probably be assisted by air- 
mechanics ' tickling ' them. 

"One way out of the trouble is to fit drip tins under the jet 
chamber to catch the gasoline as it falls. This is all very well 
just to prevent fire while the machine is being started up, but it 
will not save it if it is left standing with the tail on the ground 
and the petrol turned on, for the drip tins will then fill up and 
run over. And if it catches then, the contents of the drip tins 
merely add fuel to the fire. 

Reversing Carburetors 

"Yet another way is to turn the carburetors round, so that 
the float chambers are behind the jets, and so come below them 
when the tail is on the ground, thus cutting off the gasoline low 
down in the jets. There seems to be no particular mechanical 
difficulty about this, though I must confess that I did not note 
very carefully whether the reversal of the float chambers would 
make them foul any other fittings on the engine. It has been 
argued, however, that doing this would starve the engine of gaso- 
line when climbing at a steep angle, as the gasoline would then 
be lowered in the jets and need more suction to get into the 
cylinders. This is rather a pretty point of amateur motor me- 
chanics to discuss, for, obviously, when the same engine is used 
as a ' pusher' instead of a tractor, the jets are in front of the 
floats, and there seems to be no falling off in power. 

Starvation of Mixture 

"Moreover, the higher a machine goes the lower is the atmos- 
pheric pressure, and, consequently, the less is the amount of air 
sucked in at each induction stroke. This means, of course, that 
with the gasoline supply the mixture at high altitudes is too 
rich, so that, in order to get precisely the right mixture when very 
high up, it is necessary to reduce the gasoline supply by screwing 
down the needle valve between the tank and the carburetor — at 
least, that has been the experience of various high-flying pilots. 
No doubt something might be done in the way of forced air feed 
to compensate for reduced atmospheric pressure, but it remains 
to be proved whether the extra weight of mechanism involved 
would pay for the extra power obtained. Variable compression 
might do something, also, to even things up, but here, also, weight 
of mechanism has to be considered. 

"In any case, at present, the higher one goes the more the 



150 Aviation Engines 

power of the engine is reduced, for less air means a less volume 
of mixture per cylinder, and as the petrol feed has to be starved 
to suit the smaller amount of air available, this means further loss 
of power. I do not know whether anyone has evolved a carbu- 
retor which automatically starves the gasoline feed when high up, 
but it seems possible that when an airplane is sagging about 'up 
against the ceiling' — as a French pilot described the absolute 
limit of climb for his particular machine — it might be a good 
thing to have the jets in front of the float chamber, for then a 
certain amount of automatic starvation would take place. 

"When a machine is right up at its limiting height, and the 
pilot is doing his best to make it go higher still, it is probably 
flying with its tail as low as the pilot dares to let it go, and the 
lateral and longitudinal controls are on the verge of vanishing, 
so that if the carburetor jets are behind the float chambers there 
is bound to be an over-rich mixture in any case. There is even 
a possibility of a careless or ignorant pilot carrying on in this tail- 
down position till one set of cylinders cuts out altogether, in which 
case the carburetor feeding that set may flood over, just as if the 
machine were on the ground, and the whole thing may catch fire. 
Whereas, with the jets in front of the floats, though the mixture 
may starve a trifle, there is, at any rate, no danger of fire through 
climbing with the tail down. 

A Diving Danger 

"On the other hand, in a 'pusher' with this type of engine, 
if the jets are in their normal position — which is in front of the 
floats — there is danger of fire in a dive. That is to say, if the 
pilot throttles right down, or switches off and relies on air pres- 
sure on his propeller to start the engine again, so that the gasoline 
is flooding over out of the jets instead of being sucked into the 
engine, there may be flooding over the magnetos if the dive is very 
steep and prolonged. In any case, a long dive will mean a certain 
amount of flooding, and, probably, a good deal of choking and 
spitting by the engine before it gets rid of the over-rich mixture 
and picks up steady firing again. Which may indicate to young 
pilots that it is not good to come down too low under such cir- 
cumstances, trusting entirely to their engines to pick up at once 
and get going before they hit the ground. 

"On the whole, it seems that it might be better practice to set 
the carburetors thwartwise of engines, for then jets and floats 
would always be at approximately the same level, no matter what 
the longitudinal position of the machine, and it is never long 
enough in one position at a big lateral angle to raise any serious 
carburetor troubles. Car manufacturers who dive cheerfully into 



Notes on Carburetor Adjustment 151 

the troubled waters of aero-engine designs are a trifle apt to forget 
that their engines are put into positions on airplanes which 
would be positively indecent in a motor car. An angle of 1 in 10 
is the exception on a car, but it is common on an airplane, and 
no one ever heard of a car going down a hill of 10 to 1 — which is 
not quite a vertical dive. Therefore, there is every excuse for a 
well-designed and properly brought-up carburetor misbehaving 
itself in an aeroplane. 

"It seems, then, that it is up to the manufacturers to produce 
better carburetors — say, with the jet central with the float. But 
it also behooves the user to show ordinary common sense in han- 
dling the material at present available, and not to make a prac- 
tice of burning up $25,000 worth or so of airplane just because 
he is too lazy to turn off his gasoline, or to have the tail of his 
machine lifted up while he is tinkering with his engines." 

XOTES OX CARBURETOR ADJUSTMENT 

The modern float feed carburetor is a delicate and 
nicely balanced appliance that requires a certain amount 
of attention and care in order to obtain the best results. 
The adjustments can only be made by one possessing an 
intelligent knowledge of carburetor construction and must 
never be made unless the reason for changing the old ad- 
justment is understood. Before altering the adjustment 
of the leading forms of carburetors, a few hints regarding 
the quality to be obtained in the mixture should be given 
some consideration, as if these are properly understood 
this knowledge will prove of great assistance in adjusting 
the vaporizer to give a good working proportion of fuel 
and air. There is some question regarding the best mix- 
ture proportions and it is estimated that gas will be 
explosive in which the proportions of fuel vapor and air 
will vary from one part of the former to a wide range 
included between four and eighteen parts of the latter. 
A one to four mixture is much too rich, while the one 
in eighteen is much too lean to provide positive ignition. 

A rich mixture should be avoided because the excessive 
fuel used w r ill deposit carbon and will soot the cylinder 
walls, combustion chamber interior, piston top and valves 
and also tend to overheat the motor. A rich mixture will 



152 Aviation Engines 

also seriously interfere with flexible control of the engine, 
as it will choke up on low throttle and run well on open 
throttle when the full amount of gas is needed. A rich 
mixture may be quickly discovered by black smoke issuing 
from the muffler, the exhaust gas having a very pungent 
odor. If the mixture contains a surplus of air there will 
be popping sounds in the carburetor, which is commonly 
termed "blowing back." To adjust a carburetor is not 
a difficult matter when the purpose of the various control 
members is understood. The first thing to do in adjusting 
a carburetor is to start the motor and to retard the spark- 
ing lever so the motor will run slowly leaving the throttle 
about half open. In order to ascertain if the mixture is 
too rich cut down the gasoline flow gradually by screwing 
down the needle valve until the motor commences to run 
irregularly or misfire. Close the needle valves as far as 
possible without having the engine come to a stop, and 
after having found the minimum amount of fuel gradually 
unscrew the adjusting valve until you arrive at the point 
where the engine develops its highest speed. When this 
adjustment is secured the lock nut is screwed in place so 
the needle valve will keep the adjustment. The next point 
to look out for is regulation of the auxiliary air supply on 
those types of carburetors where an adjustable air valve 
is provided. This is done by advancing the spark lever 
and opening the throttle. The air valve is first opened 
or the spring tension reduced to a point where the engine 
misfires or pops back in the carburetor. When the point 
of maximum air supply the engine will run on is thus de- 
termined, the air valve spring may be tightened by screw- 
ing in on the regulating screw until the point is reached 
where an appreciable speeding up of the engine is noticed. 
If both fuel and air valves are set right, it will be possible 
to accelerate the engine speed uniformly without interfer- 
ing with regularity of engine operation by moving the 
throttle lever or accelerator pedal from its closed to its 
wide open position, this being done with the spark lever 
"advanced. All types of carburetors do not have the same 



Notes on Carburetor Adjustment 153 

means of adjustment; in fact, some adjust only with the 
gasoline regulating needle; others must have a complete 
change of spray nozzles; while in others the mixture pro- 
portions may be varied only by adjustment of the quantity 
of entering air. Changing the float level is effective in 
some carburetors, but this should never be done unless it 
is certain that the level is not correct. Full instructions 
for locating carburetion troubles will be given in proper 
sequence. 

It is a fact well known to experienced repairmen and 
motorists that atmospheric conditions have much to do 
with carburetor action. It is often observed that a motor 
seems to develop more power at night than during the 
day, a circumstance which is attributed to the presence of 
more moisture in the cooler night air. Likewise, taking 
a motor from sea level to an altitude of 10,000 feet in- 
volves using rarefied air in the engine cylinders and at- 
mospheric pressures ranging from 14.7 pounds at sea 
level to 10.1 pounds per square inch at the high altitude. 
All carburetors will require some adjustment in the course 
of any material change from one level to another. Great 
changes of altitude also have a marked effect on the cool- 
ing system of an airplane. Water boils at 212 degrees F. 
only at sea level. At an altitude of 10,000 feet it will 
boil at a temperature nineteen degrees lower, or 193 de- 
grees F. 

In high altitudes the reduced atmospheric pressure, 
for 5,000 feet or higher than sea level, results in not 
enough air reaching the mixture, so that either the auxil- 
iary air opening has to be increased, or the gasoline in 
the mixture cut down. If the user is to be continually 
at high altitudes he should immediately purchase either 
a larger dome or a smaller strangling tube, mentioning 
the size carburetor that is at present in use and the type 
of motor that it is on, including details as to the bore 
and stroke. The smaller strangling tube makes an in- 
creased suction at the spray nozzle; the air will have to 
be readjusted to meet it and you can use more auxiliary 



154 Aviation Engines 

air, which is necessary. The effect on the motor without 
a smaller strangling tube is a perceptible sluggishness and 
failure to speed up to its normal crank-shaft revolutions, 
as well as failure to give power. It means that about one- 
third of the regular speed is cut out. The reduced at- 
mospheric pressure reduces the power of the explosion, 
in that there is not the same quantity of oxygen in the 
combustion chamber as at sea level ; to increase the amount 
taken in, you must also increase the gasoline speed, which 
is done by an increased suction through the smaller stran- 
gling aperture. Some forms of carburetors are affected 
more than others by changes of altitude, which explains 
why the Zenith is so widely employed for airplane engine 
use. The compensating nozzle construction is not influ- 
enced as much by changes of altitude as the simpler nozzle 
types are. 



CHAPTER VI 

Early Ignition Systems — Electrical Ignition Best — Fundamentals of 
Magnetism Outlined — Forms of Magneto — Zones of Magnetic In- 
fluence — How Magnets are Made — Electricity and Magnetism 
Related — Basic Principles of Magneto Action — Essential Parts of 
Magneto and Functions — Transformer Coil Systems — True High 
Tension Type — The Berling Magneto — Timing and Care — The 
Dixie Magneto — Spark Plug Design and Application — Two-Spark 
Ignition — Special Airplane Plug. 

EARLY IGSTITIOK SYSTEMS 

Oxe of the most important auxiliary groups of the 
gasoline engine comprising the airplane power plant and 
one absolutely necessary to insure engine action is the 
ignition system or the method employed of kindling the 
compressed gas in the cylinder to produce an explosion 
and useful power. The ignition system has been fully 
as well developed as other parts of the engine, and at 
the present time practically all ignition systems follow 
principles which have become standard through wide ac- 
ceptance. 

During the early stages of development of the gasoline 
engine various methods of exploding the charge of com- 
bustible gas in the cylinder were employed. On some of 
the earliest engines a flame burned close to the cylinder 
head, and at the proper time for ignition a slide or valve 
moved to provide an opening which permitted the flame 
to ignite the gas back of the piston. This system was 
practical only on the primitive form of gas engines in 
which the charge was not compressed before ignition. 
Later, when it was found desirable to compress the gas 
a certain degree before exploding it, an incandescent plat- 
inum tube in the combustion chamber, which was kept 
in a heated condition by a flame burning in it, exploded 
the gas. The naked flame was not suitable in this appli- 

155 



156 Aviation Engines 

cation because when the slide was opened to provide com- 
munication between the flame and the gas the compressed 
charge escaped from the cylinder with enough pressure to 
blow out the flame at times and thus cause irregular ig- 
nition. When the flame was housed in a platinum tube 
it was protected from the direct action of the gas, and 
as long as the tube was maintained at the proper point 
of incandescence regular ignition was obtained. 

Some engineers utilized the property of gases firing 
themselves if compressed to a sufficient degree, while 
others depended upon the heat stored in the cylinder-head 
to fire the highly compressed gas. None of these methods 
were practical in their application to motor car engines 
because they did not permit flexible engine action which 
is so desirable. At the present time, electrical ignition 
systems in which the compressed gas is exploded by the 
heating value of the minute electric arc or spark in the 
cylinder are standard, and the general practice seems to 
be toward the use of mechanical producers of electricity 
rather than chemical batteries. 

ELECTRICAL IGNITION" BEST 

Two general forms of electrical ignition systems may 
be used, the most popular being that in which a current 
of electricity under high tension is made to leap a gap 
or air space between the points of the sparking plug 
screwed into the cylinder. The other form, which has 
been almost entirely abandoned in automobile and which 
was never used with airplane engine practice, but which 
is still used to some extent on marine engines, is called 
the low-tension system because current of low voltage is 
used and the spark is produced by moving electrodes in 
the combustion chamber. 

The essential elements of any electrical ignition sys- 
tem, either high or low tension, are: First, a simple and 
practical method of current production; second, suitable 
timing apparatus to cause the spark to occur at the right 
point in the cycle of engine action; third, suitable wiring 



Fundamentals of Magnetism 157 

and other apparatus to convey the current produced by 
the generator to the sparking member in the cylinder. 

The various appliances necessary to secure prompt ig- 
nition of the compressed gases should be described in some 
detail because of the importance of the ignition system. 
It is patent that the scope of a work of this character 
does not permit one to go fully into the theory and prin- 
ciples of operation of all appliances which may be used 
in connection with gasoline motor ignition, but at the same 
time it is important that the elementary principles be 
considered to some extent in order that the reader should 
have a proper understanding of the very essential ignition 
apparatus. The first point considered will be the common 
methods of generating the electricity, then the appliances 
to utilize' it and produce the required spark in the cylin- 
der. Inasmuch as magneto ignition is universally used 
in connection with airplane engine ignition it will not be 
necessary to consider battery ignition systems. 

FUNDAMENTALS OF MAGNETISM OUTLINED 

To properly understand the phenomena and forces in- 
volved in the generation of electrical energy by mechanical 
means it is necessary to become familiar with some of the 
elementary principles of magnetism and its relation to 
electricity. The following matter can be read with profit 
by those who are not familiar with the subject. Most 
persons know that magnetism exists in certain substances, 
but many are not able to grasp the terms used in describ- 
ing the operation of various electrical devices because of 
not possessing a knowledge of the basic facts upon which 
the action of such apparatus is based. 

Magnetism is a property possessed by certain sub- 
stances and is manifested by the ability to attract and 
repel other materials susceptible to its effects. When this 
phenomenon is manifested by a conductor or wire through 
which a current of electricity is flowing it is termed "elec- 
tro-magnetism. ' ' Magnetism and electricity are closely 
related, each being capable of producing the other. Prac- 



158 Aviation Engines 

tically all of the phenomena manifested by materials which 
possess magnetic qualities naturally can be easily repro- 
duced by passing a current of electricity through a body 
which, when not under electrical influence, is not a mag- 
netic substance. Only certain substances show magnetic 
properties, these being iron, nickel, cobalt and their alloys. 

The earliest known substance possessing magnetic 
properties was a stone first found in Asia Minor. It 
was called the lodestone or leading stone, because of its 
tendency, if arranged so it could be moved freely, of point- 
ing one particular portion toward the north. The compass 
of the ancient Chinese mariners was a piece of this mate- 
rial, now known to be iron ore, suspended by a light thread 
or floated on a cork in some liquid so one end would point 
toward the north magnetic pole of the earth. The reason 
that this stone was magnetic was hard to define for a 
time, until it was learned that the earth was one huge 
magnet and that the iron ore, being particularly suscep- 
tible, absorbed and retained some of this magnetism. 

Most of us are familiar with some of the properties of 
the magnet because of the extensive sale and use of small 
horseshoe magnets as toys. As they only cost a few pen- 
nies every one has owned one at some time or other and 
has experimented with various materials to see if they 
would be attracted. Small pieces of iron or steel were 
quickly attracted to the magnet and adhered to the pole 
pieces when brought within the zone of magnetic influence. 
It was soon learned that brass, copper, tin or zinc were 
not affected by the magnet. A simple experiment that 
serves to illustrate magnetic attraction of several sub- 
stances is shown at A, Fig. 57. In this, several balls are 
hung from a standard or support, one of these being of 
iron, another of steel. When a magnet is brought near 
either of these they will be attracted toward it, while the 
others will remain indifferent to the magnetic force. 
Experimenters soon learned that of the common metals 
only iron or steel were magnetic. 

If the ordinary bar or horseshoe magnet be carefully 



Magnetic Influence Defined 



159 



examined, one end will be fonnd to be marked N. This 
indicates the north pole, while the other end is not usually 
marked and is the south pole. If the north pole of one 
magnet is brought near the south pole of another, a strong 
attraction will exist between them, this depending upon 




Iron Attracted by Magnet, 
Forms of Magnets. 



Bar 



S Simpl 

N. 



Horseshoe 




S Compound 



Filings (Iron) Adhering 
to Magnets. 




Bar Magnet 



(T\ 



s 




Attraction Between Magnets. 

Fields of Magnetic Influence, 

Bar Magnet. 






V ) »» \\\ 






'£. 









Horseshoe Magnet* 




Fig. 57. — Some Simple Experiments to Demonstrate Various Magnetic Phe- 
nomena and Clearly Outline Effects of Magnetism and Various Forms 
of Magnets. 



160 Aviation Engines 

the size of the magnets used and the air gap separating 
the poles. If the south pole of one magnet is brought 
close to the end of the same polarity of the other there 
will be a pronounced repulsion of like force. These facts 
are easily proved by the simple experiment outlined at 
B, Fig. 57. A magnet will only attract or influence a 
substance having similar qualities. The like poles of 
magnets will repel each other because of the obvious im- 
possibility of uniting two influences or forces of practi- 
cally equal strength but flowing in opposite directions. 
The unlike poles of magnets attract each other because 
the force is flowing in the same direction. The flow of 
magnetism is through the magnet from south to north and 
the circuit is completed by the flow of magnetic influence 
through the air gap or metal armature bridging it from 
the north to the south pole. 

FORMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE 

DEFINED 

Magnets are commonly made in two forms, either in 
the shape of a bar or horseshoe. These two forms are 
made in two types, simple or compound. The latter are 
composed of a number of magnets of the same form united 
so the ends of like polarity are laced together, and such 
a construction will be more efficient and have more strength 
than a simple magnet of the same weight. The two com- 
mon forms of simple and compound magnets are shown 
at C, Fig. 57. The zone in which a magnetic influence 
occurs is called the magnetic field, and this force can be 
graphically shown by means of imaginary lines, which 
are termed " lines of force.' ' As will be seen from the 
diagram at D, Fig. 57, the lines show the direction of 
action of the magnetic force and also show its strength, 
as they are closer together and more numerous when the 
intensity of the magnetic field is at its maximum. A 
simple method of demonstrating the presence of the force 
is to lay a piece of thin paper over the pole pieces of either 
a bar or horseshoe magnet and sprinkle fine iron filings 



Magnets and Zone of Influence 161 

on it. The particles of metal arrange themselves in very 
much the manner shown in the illustrations and prove 
that the magnetic field actually exists. 

The form of magnet used will materially affect the 
size and area of the magnetic field. It will be noted that 
the field will be concentrated to a greater extent with 
the horseshoe form because of the proximity of the poles. 
It should be understood that these lines have no actual 
existence, but are imaginary and assumed to exist only 
to show the way the magnetic field is distributed. The 
magnetic influence is always greater at the poles than 
at the center, and that is why a horseshoe or U-form 
magnet is used in practically all magnetos or dynamos. 
This greater attraction at the poles can be clearly dem- 
onstrated by sprinkling iron filings on bar and U mag- 
nets, as outlined at E, Fig. 57. A large mass gathers at 
the pole pieces, gradually tapering down toward the point 
where the attraction is least. 

From the diagrams it will be seen that the flow of 
magnetism is from one pole to the other by means of 
curved paths between them. This circuit is completed 
by the magnetism flowing from one pole to the other 
through the magnet, and as this flow is continued as long 
as the body remains magnetic it constitutes a magnetic 
circuit. If this flow were temporarily interrupted by 
means of a conductor of electricity moving through the 
field there would be a current of electricity induced in 
the conductor every time it cut the lines of force. There 
are three kinds of magnetic circuits. A non-magnetic 
circuit is one in which the magnetic influence completes 
its circuit through some substance not susceptible to the 
force. A closed magnetic circuit is one in which the in- 
fluence completes its circuit through some magnetic ma- 
terial which bridges the gap between the poles. A com- 
pound circuit is that in which the magnetic influence 
passes through magnetic substances and non-magnetic sub- 
stances in order to complete its circuit. 



162 Aviation Engines 



HOW IKON AND STEEL BARS ARE MADE MAGNETIC 

Magnetism may be produced in two ways, by contact 
or induction. If a piece of steel is rubbed on a magnet 
it will be found a magnet when removed, having a north 
and south pole and all of the properties found in the 
energizing magnet. This is magnetizing by contact. A 
piece of steel will retain the magnetism imparted to it for 
a considerable length of time, and the influence that re- 
mains is known as residual magnetism. This property 
may be increased by alloying the steel with tungsten and 
hardening it before it is magnetized. Any material that 
will retain its magnetic influence after removal from the 
source of magnetism is known as a permanent magnet. 
If a piece of iron or steel is brought into the magnetic 
field of a powerful magnet it becomes a magnet, without 
actual contact with the energizer. This is magnetizing 
by magnetic induction. If a powerful electric current 
flows through an insulated conductor wound around a 
piece of iron or steel it will make a magnet of it. This 
is magnetizing by electro-magnetic induction. A magnet 
made in this manner is termed an electro-magnet and 
usually the metal is of such a nature that it will not 
retain its magnetism when the current ceases to flow 
around it. Steel is used in all cases where permanent 
magnets are required, while soft iron is employed in all 
cases where an intermittent magnetic action is desired. 
Magneto field magnets are always made of tungsten steel 
alloy, so treated that it will retain its magnetism for 
lengthy periods. 

ELECTRICITY AND MAGNETISM CLOSELY RELATED 

There are many points in which magnetism and elec- 
tricity are alike. For instance, air is a medium that of- 
fers considerable resistance to the passage of both mag- 
netic influence and electric energy, although it offers more 
resistance to the passage of the latter. Minerals like 
iron or steel are very easily influenced by magnetism and 



Principles of Magneto Outlined 163 

easily penetrated by it. "When one of these is present 
in the magnetic circuit the magnetism will flow through 
the metal. Any metal is a good conductor for the pas- 
sage of the electric current, but few metals are good 
conductors of magnetic energy. A body of the proper 
metal will become a magnet due to induction if placed 
in the magnetic field, having a south pole where the lines 
of force enter it and a north pole where they pass out. 

We have seen that a magnet is constantly surrounded 
by a magnetic field and that an electrical conductor when 
carrying a current is also surrounded by a field of mag- 
netic influence. Now if the conductor carrying a current 
of electricity will induce magnetism in a bar of iron or 
steel, by a reversal of this process, a magnetized iron or 
steel bar will produce a current of electricity in a con- 
ductor. It is upon this principle that the modern dynamo 
or magneto is constructed. If an electro-motive force is 
induced in a conductor by moving it across a field of mag- 
netic influence, or by passing a magnetic field near a 
conductor, electricity is said to be generated by magneto- 
electric induction. All mechanical generators of the elec- 
tric current using permanent steel magnets to produce a 
field of magnetic influence are of this type. 

BASIC PRINCIPLES OF MAGNETO OUTLINED 

The accompanying diagram, Fig. 58, will show these 
principles very clearly. As stated on an earlier page, 
if the lines of force in the magnetic field are cut by a 
suitable conductor an electrical impulse mil be produced 
in that conductor. In this simple machine the lines of 
force exist between the poles of a horseshoe magnet. The 
conductor, which in this case is a loop of copper wire, 
is mounted upon a spindle in order that it may be rotated 
in the magnetic field to cut the lines of magnetic influ- 
ence present between the pole pieces. Both of the ends 
of this loop are connected, one with the insulated drum 
shown upon the shaft, the other to the shaft. Two metal 
brushes are employed to collect the current and cause it 



164 



Aviation Engines 



to flow through the external circuit. It can be seen that 
when the shaft is turned in the direction of the arrow 
the loop will cut through the lines of magnetic influence 
and a current will be generated therein. 




Insulated Ring' 
Loop of Wire' 
Spindle' 

Brushes* 



Fig. 58. — Elementary Form of Magneto Showing Principal Parts Simplified 
to Make Method of Current Generation Clear. 

The pressure of the current and the amount produced 
vary in accordance to the rapidity with which the lines 
of magnetic influence are cut. The armature of a practi- 
cal magneto, therefore, differs materially from that shown 
in the diagram. A large number of loops of wire would 
be mounted upon this shaft in order that the lines of 
magnetic influence would be cut a greater number of times 
in a given period and a core of iron used as a backing 



Magneto Operating Principles 



165 



for the wire. This would give a more rapid alternating 
current and a higher electro-motive force than would be 
the case with a smaller number of loops of wire. 

The illustrations at Fig. 59 show a conventional double 




Secondary 
Winding^ 



Primary 




mm^mmm 



Armature 

Pole I Pole 

Pieces ^J—^. Pieces 





wmmmmmmm 





Fig. 59. — Showing How Strength of Magnetic Influence and of the Currents 
Induced in the Windings of Armature Vary with the Rapidity of 
Changes of Flow. 



166 Aviation Engines 

winding armature and field magnetic of a practical mag- 
neto in part section and will serve to more fully em- 
phasize the points previously made. If the armature or 
spindle were removed from between the pole pieces there 
would exist 'a field of magnetic influence as shown at Fig. 
57, but the introduction of this component provides a 
conductor (the iron core) for the magnetic energy, re- 
gardless of its position, though the facility with which 
the influence will be transmitted depends entirely upon 
the position of the core. As shown at A, the magnetic 
flow is through the main body in a straight line, while 
at B, which position the armature has attained after one- 
eighth revolution, or 45 degrees travel in the direction 
of the arrow, the magnetism must pass through in the 
manner indicated. At C, which position is attained every 
half revolution, the magnetic energy abandons the longer 
path through the body of the core for the shorter passage 
offer 3d by the side pieces, and the field thrown out by the 
cross bar disappears. On further rotation of the arma- 
ture, as at D, the body of the core again becomes ener- 
gized as the magnetic influence resumes its flow through 
it. These changes in the strength of the magnetic field 
when distorted by the armature core, as well as the in- 
tensity of the energy existing in the field, affect the 
windings, and the electrical energy induced therein cor- 
responds in strength to the rapidity with which these 
changes in magnetic Aoav occur. The most pronounced 
changes in the strength of the field will occur as the ar- 
mature passes from position B to D, because the magnetic 
field existing around the core will be destroyed and again 
re-established. 

During the most, of the armature rotation the changes 
in strength will be slight and the currents induced in the 
wire correspondingly small; but at the instant the core 
becomes remagnetized, as the armature leaves position C, 
the current produced will be at its maximum, and it is nec- 
essary to so time the rotation of the armature that at this 
instant one of the cylinders is in condition to be fired. It 



Essential Parts of a Magneto 167 

is imperative that the armature be driven in such relation 
to the crank-shaft that each production of maximum cur- 
rent coincides with the ignition point, this condition exist- 
ing twice during each revolution of the armature, or at 
every 180 degrees travel. Each position shown corre- 
sponds to 45 degrees travel of the armature, or one-eighth 
of a turn, and it takes just three-eighths revolution to 
change the position from A to that shown at D. 

ESSEXTLAL PARTS OF A MAGXETO AXD THEIR FTJXCTI0XS 

The magnets which produce the influence that in turn 
induces the electrical energy in the winding or loops of 
wire on the armature, and which may have any even 
number of opposed poles, are called field magnets. The 
loops of wire which are mounted upon a suitable drum 
and rotate in the field of magnetic inflence in order to 
cut the lines of force is called an armature winding, while 
the core is the metal portion. The entire assembly is 
called the armature. The exposed ends of the magnets 
are called pole pieces and the arrangement used to collect 
the current is either a commutator or a collector. The 
stationary pieces which bear against the collector or com- 
mutator and act as terminals for the outside circuit are 
called brushes. These brushes are often of copper, or 
some of its alloys, because copper has a greater electrical 
conductivity than any other metal. 

These brushes are nearly always of carbon, which 
is sometimes electroplated with copper to increase its 
electrical conductivity, though cylinders of copper wire 
gauze impregnated with graphite are utilized at times. 
Carbon is used because it is not so liable to cut the metal 
of the commutator as might be the case if the contact was 
of the metal to metal type. The reason for this is that 
carbon has the peculiar property in that it materially as- 
sists in the lubrication of the commutator, and being of 
soft, unctuous composition, will wear and conform to any 
irregularities on the surface of the metal collector rings. 

The magneto in common use consists of a number of 



168 Aviation Engines 

horseshoe magnets which are compound in form and at- 
tached to suitable cast-iron pole pieces used to collect and 
concentrate the magnetic influence of the various magnets. 
Between these pole pieces an armature rotates. This is 
usually shaped like a shuttle, around which are wound 
coils of insulated wire. These are composed of a large 
number of turns and the current produced depends in 
great measure upon the size of the wire and the number 
of turns per coil. An armature winding of large wire will 
deliver a current of great amperage, but of small voltage. 
An armature wound with very fine wire will deliver a 
current of high voltage but of low amperage. In the 
ordinary form of magneto, such as used for ignition, the 
current is alternating in character and the break in the 
circuit should be timed to occur when the armature is at 
the point of its greatest potential or pressure. Where 
such a generator is designed for direct current production 
the ends of the winding are attached to the segments of 
a commutator, but where the instrument is designed to 
deliver an alternating current one end of the winding is 
fastened to an insulator ring on one end of the armature 
shaft and the other end is grounded on the frame of the 
machine. 

The quantity of the current depends upon the strength 
of the magnetic field and the number of lines of magnetic 
influence acting through the armature. The electro-motive 
force varies as to the length of the armature winding and 
the number of revolutions at which the armature is rotated. 

THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO 

The magneto in the various systems which employ a 
transformer coil is very similar to a low-tension genera- 
tor in general construction, and the current delivered at 
the terminals seldom exceeds 100 volts. As it requires 
many times that potential or pressure to leap the gap 
which exists between the points of the conventional spark 
plug, a separate coil is placed in circuit to intensify the 
current to one of greater capacity. The essential parts 



Transformer Coil-Magneto System 



169 



of such, a system and their relation to each other are 
shown in diagrammatic form at Fig. 60 and as a com- 
plete system at Fig. 61. As is true of other systems the 
magnetic influence is produced by permanent steel mag- 
nets clamped to the cast-iron pole pieces between which 
the armature rotates. At the point of greatest potential 






f<L4-4-$xi > l 



[■ Wires to the Plugs /\ S^~_ 




Distributor Plate 
Distributor Arm 



Contact Breaker L_ 



Cam 



Primary Winding 
Secondary Winding 




Armature 



Cam B 



Ground 



Transformer Coll Interrupter 

Adjustment / \6rounded 

insulated Contact 
Contact 



Tig. 60. — Diagrams Explaining Action of Low Tension Transformer Coil and 
True High Tension Magneto Ignition Systems. 

in the armature winding the current is broken by the 
contact breaker, which is actuated by a cam, and a cur- 
rent of higher value is induced in the secondary winding 
of the transformer coil when the low voltage current is 
passed through the primary winding. 

It will be noted that the points of the contact breaker 
are together except for the brief instant when separated 
by the action of the point of the cam upon the lever. It 
is obvious that the armature winding is short-circuited 



170 



Aviation Engines 




Transformer Coil-Magneto System 



171 



upon itself except when the contact points are separated. 
While the armature "winding is thus short-circuited there 
will be practically no generation of current. When the 
points are separated there is a sudden flow of current 
through the primary winding of the transformer coil, in- 
ducing a secondary current in the other winding, which 
can be varied in strength by certain considerations in the 



To Second Set 
Spark Plugs _ 



6 Volt Battery 





Front of Switch 



Fig. 61. — Berling Two-Spark Dual Ignition System. 

preliminary design of the apparatus. This current of 
higher potential or voltage is conducted directly to the 
plug if the device is fitted to a single-cylinder engine, or 
to the distributor arm if fitted to a multiple-cylinder mo- 
tor. The distributor consists of an insulator in which is 
placed a number of segments, one for each cylinder to 
be fired, and so spaced that the number of degrees be- 
tween them correspond to the ignition points of the motor. 
A two-cylinder motor would have two segments, a three- 
cylinder, three segments, and so on within the capacity 
of the instrument. In the illustration a four-cylinder dis- 
tributor is fitted, and the distributing arm is in contact 



172 



Aviation Engines 



with the segment corresponding to the cylinder about to 
be fired. 

TRUE HIGH-TENSION MAGNETOS ARE SELF-CONTAINED 

The true high-tension magneto differs from the pre- 
ceding inasmuch as the current of high voltage is pro- 
duced in the armature winding direct, without the use of 
the separate coil. Instead of but one coil, the armature 
carries two, one of comparatively coarse wire, the other 
of many turns of finer wire. The arrangement of these 



To Plugs Nearest 
Inlet Valves 




Ground 




Front I of 



Switch 



Fig. 62. — Berling Double-Spark Independent System. 

windings can be readily ascertained by reference, to the 
diagram B, Fig. 60, which shows the principle of opera- 
tion very clearly. The simplicity of the ignition system 
is evidently by inspection of Fig. 62. One end of the 
primary winding (coarse wire) is coupled or grounded 
to the armature core, and the other passes to the insu- 
lated part of the interrupter. While in some forms the 
interrupter or contact breaker mechanism does not re- 
volve, the desired motion being imparted to the contact 
lever to separate the points of a revolving cam, in this 
the cam or tripping mechanism is stationary and the con- 
tact breaker revolves. This arrangement makes it pos- 
sible to conduct the current from the revolving primary 
coil to the interrupter by a direct connection, eliminating 



High Tension Magnetos Self -Contained 173 

the use of brushes, which would otherwise be necessary. 
In other forms of this appliance where the winding is 
stationary, the interrupter may be operated by a revolv- 
ing cam, though, if desired, the used of a brush at this 
point will permit this construction with a revolving 
winding. 

During the revolution of the armature the grounded 
lever makes and breaks contact with the insulated point, 
short-circuiting the primary winding upon itself until the 
armature reaches the proper position of maximum in- 
tensity of current production, at which time the circuit is 
broken, as in the former instance. One end of the sec- 
ondary winding (fine wire) is grounded on the live end of 
the primary, the other end being attached to the revolv- 
ing arm of the distributor mechanism. So long as a closed 
circuit is maintained feeble currents mil pass through the 
primary winding, and so long as the contact points are 
together this condition will exist. When the current 
reaches its maximum value, because of the armature be- 
ing in the best position, the cam operates the interrupter 
and the points are separated, breaking the short circuit 
which has existed in the primary winding. 

The secondary circuit has been open while the distrib- 
utor arm has moved from one contact to another and there 
has been no flow of energy through this winding. While 
the electrical pressure will rise in this, even if the dis- 
tributor arm contacted with one of the segments, there 
would be no spark at the plug until the contact points 
separated, because the current in the secondary winding 
would not be of sufficient strength. When the interrupter 
operates, however, the maximum primary current will be 
diverted from its short circuit and can flow to the ground 
only through the secondary winding and spark-plug cir- 
cuit. The high pressure now existing in the secondary 
winding will be greatly increased by the sudden flow of 
primary current, and energy of high enough potential to 
successfully bridge the gap at the plug is thereby pro- 
duced in the winding. 



174 



Aviation Engines 



THE BEKLING MAGNETO 



The Berling magneto is a true high tension type de- 
livering two impulses per revolution, but it is made in a 
variety of forms, both single and double spark. Its prin- 
ciple of action does not differ in essentials from the high 



/•A i 


1 P 

j 


■ 

1 




m% '! Mi. 


, 







Fig. 63. — Type DD Berling High Tension Magneto. 



tension type previously described. This magneto is used 
on Curtis s aviation engines and will deliver sparks in a 
positive manner sufficient to insure ignition of engines up 
to 200 horse-power and at rotative speeds of the magneto 
armature up to 4,000 r. p. m. which is sufficient to take 
care of an eight-cylinder V engine running up to 2,000 



Berling Ignition Magneto 175 

r. p. m. The magneto is driven at crank- shaft speed on 
f onr-cylinder engines, at 1% times crank-shaft speed on six- 
cylinder engines and at twice crank-shaft speed on eight- 
cylinder V types. The types "D" and "DD" BER- 
LING- Magnetos are interchangeable with corresponding 
magnetos of other standard makes. The dimensions of 
the four-, six- and eight-cylinder types "D" and "DD" 
are all the same. 

The ideal method of driving the magneto is by means 
of flexible direct connecting coupling to a shaft intended 
for the purpose of driving the magneto. As the magneto 
must be driven at a high speed, a coupling of some 
flexibility is preferable. The employment of such a coup- 
ling will facilitate the mounting of the magneto, because 
a small inaccuracy in the lining up of the magneto with 
the driving shaft will be taken care of by the flexible 
coupling, whereas with a perfectly rigid coupling the 
line-up of the magneto must be absolutely accurate. An- 
other advantage of the flexible coupling is that the vibra- 
tion of the motor will not be as fully transmitted to the 
armature shaft on the magneto as in case a rigid coup- 
ling is used. This means prolonged life for the magneto. 

The next best method of driving the magneto is by 
means of a gear keyed to the armature shaft. When 
this method of driving is employed, great care must be 
exercised in providing sufficient clearance between the 
gear on the magneto and the driving gear. If there 
should be a tight spot between these two gears it will 
react disadvantageously on the magneto. The third 
available method is to drive the magneto by means of 
a chain. This is the least desirable of the three methods 
and should be resorted to only in case of absolute neces- 
sity. It is difficult to provide sufficient clearance when 
using a chain without rendering the timing less accurate 
and positive. 

Fig. "64, A" shows diagrammatically the circuit of the 
"D" type two-spark independent magneto and the switch 
used with it. In position OFF the primary winding 



176 



Aviation Engines 



of the magneto is short-circuited and in this position 
the switch serves as an ordinary cut-ont or grounding 
switch. In position "1" the switch connects the mag- 
neto in such a way that it operates as an ordinary 
single-spark magneto. In this position one end of the 



Distributor 
Ffnge/\^ 



Distributor | 
Finger - N 



— Primary Circuit 

Secondary » 

Ground ( Frame) 




Back View 
of Swrfch 



Magneto Interrupter'' '' Battery Timer 
B 



Fig. 64. — Wiring" Diagrams of Berling Magneto Ignition Systems. 



secondary winding is grounded to the body of the motor. 
This is the starting position. In this position of the 
switch the entire voltage generated in the magneto is 
concentrated at one spark-plug instead of being divided 
in half. With the motor turning over very slowly, as is 
the case in starting, the full voltage generated by the 



Berling Ignition Magneto 177 

magneto will not in all cases be sufficient to bridge simul- 
taneously two spark gaps, but is amply sufficient to 
bridge one. Also, this position of the switch tends to 
retard the ignition and should be used in starting to 
prevent back-firing. With the switch in position "2" 
the magneto applies ignition to both plugs in each 
cylinder simultaneously. This is the normal running 
position. 

Fig. 64, B shows diagrammatically the circuit of the 
type "DD" BEKLINGr high-tension two-spark dual mag- 
neto. This type is recommended for certain types of 
heawy-duty airplane motors, which it is impossible to turn 
over fast enough to give the magneto sufficient speed to 
generate even a single spark of volume great enough to 
ignite the gas in the cylinder. The dual feature consists 
of the addition to the magneto of a battery interrupter. 
The equipment consists of the magneto, coil and special 
high-tension switch. The coil is intended to operate on 
six volts. Either a storage battery or dry cells may be 
used. 

With the switch in the OFF position, the magneto is 
grounded, and the battery circuit is open. With the 
switch in the second or battery position marked "BAT," 
one end of the secondary winding of the magneto is 
grounded, and the magneto operates as a single-spark 
magneto delivering high-tension current to the inside 
distributor, and the battery circuit being closed the high- 
tension current from the coil is delivered to the outside 
distributor. In this position the battery current is sup- 
plied to one set of spark plugs, no matter how slowly 
the motor is turned over, but as soon as the motor starts, 
the magneto supplies current as a single-spark magneto 
to the other set of the spark-plugs. After the engine is 
running, the switch should be thrown to the position 
marked "MAG." The battery and coil are then dis- 
connected, and the magneto furnishes ignition to both 
plugs in each cylinder. This is the normal running 
position. Either a non- vibrating coil type "N-l" is 



178 Aviation Engines 

furnished or a combined vibrating and non-vibrating coil 
type "VN-1." 

SETTING BERLING MAGNETO 

The magneto may be set according to one of two 
different methods, the selection of which is, to some 
extent, governed by the characteristics of the engine, 
but largely due to the personal preference on the part 
of the user. In the first method described below, the 
most advantageous position of the piston for fully ad- 
vanced ignition is determined in relation to the extreme 
advanced position of the magneto. In this case, the 
fully retarded ignition will not be a matter of selection, 
but the timing range of the magneto is wide enough to 
bring the fully retarded ignition after top-center position 
of the piston. The second method for the setting of the 
magneto fixes the fully retarded position of the magneto 
in relation to that position of the piston where fully 
retarded ignition is desired. In this case, the extreme 
advance position of the magneto will not always corre- 
spond with the best position of the piston for fully ad- 
vanced ignition, and the amount of advance the magneto 
should have to meet ideal requirements in this respect 
must be determined by experiment. 

First Method: 

1. Designate one cylinder as cylinder No. 1. 

2. Turn the crank-shaft until the piston in cylinder 
No. 1 is in the position where the fully advanced spark 
is desired to occur. 

3. Eemove the cover from the distributor block and 
turn the armature shaft in the direction of rotation of the 
magneto until the distributor finger-brush comes into 
such a position that this brush makes contact with the 
segment which is connected to the cable terminal marked 
"1." This is either one of the two bottom segments, 
depending upon the direction of rotation. 

4. Place the cam housing in extreme advance, i.e., 



Timing Berling Magneto 179 

turn the cam housing until it stops, in the direction 
opposite to the direction of rotation of the armature. 
With the cam housing in this position, open the cover. 

5. With the armature in the approximate position as 
described in "3," turn the armature slightly in either 
direction to such a point that the platinum points of the 
magneto interrupter will just begin to open at the end 
of the cam, adjacent to the fibre lever on the interrupter. 

6. "With this exact position of the armature, fix the 
magneto to the driving member of the engine. 

Second Method: 

1. Designate one cylinder as cylinder No. 1. 

2. Turn the crank-shaft until the piston in cylinder 
No. 1 is in the position at which the fully retarded spark 
is desired to occur. 

3. Same as No. 3 under First Method. 

4. Place the cam housing in extreme retard, i.e., turn 
the cam housing until it stops, in the same direction as 
the direction of rotation of the armature. With the cam 
housing in this position, open the cover. 

5. Same as No. 5 under First Method. 

6. Same as No. 6 under First Method. 

WIRING THE MAGNETO 

The wiring of the magneto is clearly shown by wiring 
diagram. 

First determine the sequence of firing for the cylinders 
and then connect the cables to the spark plug in the 
cylinders in proper sequence, beginning with cylinder 
No. 1 marked on the distributor block. 

The switch used with the independent type must be 
mounted in such a manner that there will be a metallic 
connection between the frame of the magneto and the 
metal portion of the switch. 

It is advisable to use a separate battery, either storage 
or dry cells, as a source of current for the dual equip- 



180 Aviation Engines 

ment. Connecting to the same battery that is used with 
the generator and other electrical equipment may cause 
trouble, as a "ground" in this battery causes the coil 
to overheat. 



CARE AND MAINTENANCE 



Lubrication, 



Use only the very best of oil for the oil cups. 

Put five drops of oil in the oil cup at the driving end 
of the magneto for every fifty hours of actual running. 

Put five drops of oil in the oil cup at the interrupter 
end of the magneto, located at one side of the cam 
housing, for every hundred hours of actual running. 

Lubricate the embossed cams in the cam housing with 
a thin film of vaseline every fifty hours of actual run- 
ning. Wipe off all superfluous vaseline. Never use oil 
in the interrupter. Do not lubricate any other part of 
the interrupter. 

Adjusting the Interrupter: 

With the fibre lever in the center of one of the em- 
bossed cams, as at Fig. 65, the opening between the 
platinum contacts should be not less than .016" and not 
more than .020". The gauge riveted to the adjusting 
wrench should barely be able to pass between the con- 
tacts when fully open. The platinum contacts must be 
smoothed off with a very fine file. "When in closed posi- 
tion, the platinum contacts should make contact with 
each other over their entire surfaces. 

When inspecting the interrupter, make sure that the 
ground brush in the back of the interrupter base is 
making good contact with the surface on which it rubs. 

Cleaning the Distributor: 

The distributor block cover should be removed for 
inspection every twenty-five hours of actual running 
and the carbon deposit from the distributor finger-brush 
wiped off the distributor block by rubbing with a rag 



Locating Magneto Trouble 



181 



or piece of waste dipped in gasoline or kerosene. The 
high-tension terminal brash on the side of the magneto 
should also be carefully inspected for proper tension. 



LOCATING TROUBLE 



Trouble in the ignition system is indicated by the 
motor "missing," stopping entirely, or by inability to 
start. 

It is safe to assume that the trouble is not in the 



o ± .Cam 
Lever R eta i n i ng ; 

Spring, ^^^^^Zt~~~\ 

Contact Points V rio^ ' T"""~" r T'* -^ » <S^ 
5 eparated- . Kr/^rV^/^S^ ' ^^\\vl 


t Fibre 
.' Interrupter 
X Lever 

m 

M 

l 

7 A 7/ 
/ / // 

--Cam 


"*~wW/#///Y\Y / • "WW 


Contact Breaker;' ^fe^JL_ii^^^ 
Housing ^ ^ss^^**"- 



Tig. 65. — The Berling Magneto Breaker Box Showing Contact Points 
Separated and Interruptor Lever on Cam. 

magneto, and the carburetor, gasoline supply and spark- 
plugs should first be investigated. 

If the magneto is suspected, the first thing to do is 
to determine if it will deliver a spark. To determine 
this, disconnect one of the high-tension leads from the 
spark-plug in one of the cylinders and place it so that 
there is approximately Yi%" between the terminal and 
the cylinder frame. 

Open the pet cocks on the other cylinders to prevent 
the engine from firing and turn over the engine until 
the piston is approaching the end of the compression 



182 Aviation Engines 

stroke in the cylinder from which the cable has been 
removed. Set the magneto in the advance position and 
rapidly rock the engine over the top-center position, 
observing closely if a spark occurs between the end of 
the high-tension cable and the frame. 

If the magneto is of the dual type, the trouble may 
be either in the magneto or in the battery or coil system, 
therefore disconnect the battery and place the switch 
in the position marked "MAG." The magneto will then 
operate as an independent magneto and should spark 
in the proper manner. After this the battery system 
should be investigated. To test the operation of the 
battery and coil, examine all connections, making sure 
that they are clean and tight, and then with the switch 
in the "BAT," rock the piston slowly back and forth. 
If a type "VN-1" coil is used, a shower of sparks should 
jump between the high-tension cable terminal and the 
cylinder frame when the piston is in the correct position 
for firing. If no spark occurs, remove the cover from 
the coil and see that the vibrating tongue is free. If a 
type "N-l" coil is used, a single spark will occur. The 
battery should furnish six volts when connected to the 
coil, and this should also be verified. 

If the coil still refuses to give a spark and all con- 
nections are correct, the coil should be replaced and the 
defective coil returned to the manufacturer. 

If both magneto and coil give a spark when tested 
as just described, the spark-plugs should be investi- 
gated. To do this, disconnect the cables and remove 
the spark-plugs. Then reconnect the cables to the plugs 
and place them so that the frame portions of the plugs 
are in metallic connection with the frame of the motor. 
Then turn over the motor, thus revolving the magneto 
armature, and see if a spark is produced at the spark 
gaps of the plugs. 

The most common defects in spark-plugs are breaking 
down of the insulation, fouling due to carbon, or too large 
or small a spark gap. To clean the plugs a stiff brush 



Locating Magneto Trouble 



183 



and gasoline should be used 



about ; : 



and never less than %4 r 



The spark gap should be 
Too small a gap 
may have been caused by beads of metal forming due 
to the heat of the spark. Too long a gap may have been 
caused by the points burning off. 

If the magneto and spark plugs are in good condition 
and the engine does not run satisfactorily, the setting 



■Distrit)u.toi 
■Cover 




Rocking Field'' 



~r— Base 



Fig. 66. — The Dixie Model 60 for Six-Cylinder Airplane Engine Ignition. 

should be verified according to instructions previously 
given, and, if necessary, readjusted. 

Be careful to observe that both the type "VN-1" and 
type "N-l" coils are so arranged that the spark occurs 
on the opening of the contacts of the timer. As this is 
just the reverse of the usual operation, it should be care- 
fully noted when any change in the setting of the timer 
is made. The timer on the dual type magneto is ad- 
justed so that the battery spark occurs about 5° later 



184 



Aviation Engines 



than the magneto spark. This provides an antomatic 
advance as soon as the switch is thrown to the magneto 
position "MAG." This relative timing can be easily 
adjusted by removing the interrupter and shifting the 
cam in the direction desired. 

THE DIXIE MAGNETO 

The Dixie magneto, shown at Fig. 66, operates on a 
different principle than the rotary armature type. It is 
used on the Hall-Scott and other aviation engines. In 



4 " 
3H" 



■8.195 




(4) ''■* lt'1'..f. \i Deep 3. 8fd. Tbreadt 



Fig. 67. — Installation Dimensions of Dixie Model 60 Magneto. 



this magneto the rotating member consists of two pieces 
of magnetic material separated by a non-magnetic center 
piece. This member constitutes true rotating poles for 
the magnet and rotates in a field structure, composed of 
two laminated field pieces, riveted between two non- 
magnetic rings. The bearings for the rotating poles are 



Dixie Ignition Magneto 



185 



mounted in steel plates, which lie against the poles of the 
magnets. When the magnet poles rotate, the magnetic 
lines of force from each magnet pole are carried directly 



Ma g n ets -> 

Rotating 
Magnet Poles 



, Inductor 

Drive Shaft 




Inductor Shaft- 



^-—r Inductors or Magnet Poles 



^' K End Plates and Bearings 

The rotating element of the. Dixie magneto. In the Dixie 
there are no revolving windings.there is no moving wire 
and the parts of the magneto are reduced to a minimum. 



A.G. HkSSTROM h.V. 



Fig. 68. — The Rotating Elements of the Dixie Magneto. 



to the field pieces and through the windings, without 
reversal through the mass of the rotating member and 
with only a single air gap. There are no losses by flux 
reversal in the rotating part, such as take place in other 



186 Aviation Engines 

machines, and this is said to account for the high efficiency 
of the instrument. 

And this " Mason Principle 1 ' involved in the operation 
of the Dixie is simplified by a glance at the field struc- 
ture, consisting of the non-magnetic rings, assembled to 
which are the field pieces between which the rotating 
poles revolve (see Fig. 68). Rotating between the 
limbs of the magnets, these two pieces of magnetic mate- 
rial form true extensions to the poles of the magnets, 
and are, in consequence, always of the same polarity. 
It will be seen there is no reversal of the magnetism 
through them, and consequently no eddy current or hys- 
teresis losses which are present in the usual rotor or 
inductor types. The simplicity features of construction 
stand out prominently here, in that there are no revolving 
windings, a detail entirely differing from the orthodox 
high-tension instrument. This simplicity becomes in- 
stantly apparent when it is found that the circuit breaker, 
instead of revolving as it does in other types, is stationary 
and that the whole breaker mechanism is exposed by 
simply turning the cover spring aside and removing 
cover. This makes inspection and adjustment particu- 
larly simple, and the fact that no special tool is neces- 
sary for adjustment of the platinum points — an ordinary 
small screw-driver is the whole "kit of tools' ' needed in 
the work of disassembling or assembling — is a feature of 
some value. 

"With dust- and water-protecting casing removed, and 
one of the magnets withdrawn, as in Fig. 69, the winding 
can be seen with its core resting on the field pole pieces 
and the primary lead attached to its side. An important 
feature of the high-tension winding is that the heads are 
of insulating material, and there is not the tendency for 
the high-tension current to jump to the side as in the 
ordinary armature type magneto. The high-tension cur- 
rent is carried to the distributor by means of an insulated 
block with a spindle, at one end of which is a spring 
brush bearing directly on the winding, thus shortening 



Dixie Ignition Magneto 



187 



the path of the high-tension current and eliminating the 
use of rubber spools and insulating parts. The moving 
parts of the magneto need never be disturbed if the high- 
tension winding is to be removed. This winding con- 



Distribufor 
Cover* 



Terminals 
to Plugs i 



■Cover Retaining 
Screws 




Contact \ 
Breaker}--. 
Box J 



'- Cover A 
The whole breaker mechanism is exposed by 
simply turning the cover spring aside and 
removing cover. A screw driver is the only 
tool necessary to adjust the platinum points, 



Distributor 
Drive Gear 



High _ 
Tension 
Winding 



After removing the cover the 
magnets can be taken off-exposing 
the high tension winding. 



'Distributor Cover 




Distributor 

Brush 

Carrier, 



B **~BreakerBox 

Nothing could be simplerthan Dixie con- 
struction. By loosening nuts and turning 
clamps aside, the distributor block can be 
removed and distributor disc lifted 
out of its housing. 



jzSsl 

trf © p 



.High 
{ Tension 



Winding 



Condenser. 




By taking out four screws the con- 
denser and high tension winding 
can be readily removed. 



AJ5.H»GSTROM NY. 



Fig. 69. — Suggestions for Adjusting and Dismantling Dixie Magneto. A — 
Screw Driver Adjusts Contact Points. B — Distributor Block Removed. 
C — Taking off Magnets. D — Showing How Easily Condenser and High 
Tension Windings are Removed. 



stitutes all of the magneto windings, no external spark 
coil being necessary. The condenser is placed directly 
above the winding and is easily removable by taking out 
two screws, instead of being placed in an armature where 
it is inaccessible except to an expert, and where it cannot 
be replaced except at the factory whence it emanated. 



188 Aviation Engines 

CARE OF THE DIXIE MAGNETO 

The bearings of the magneto are provided with oil 
cups and a few drops of light oil every 1,000 miles are 
sufficient. The breaker lever should be lubricated every 
1,000 miles with a drop of light oil, applied with a tooth- 
pick. The proper distance between the platinum points 
when separated should not exceed .020 or one-fiftieth of 
an inch. A gauge of the proper size is attached to the 
screwdriver furnished with the magneto. The platinum 
contacts should be kept clean and properly adjusted. 
Should the contacts become pitted, a fine file should be 
used to smooth them in order to permit them to come 
into perfect contact. The distributor block should be 
removed occasionally and inspected for an accumulation 
of carbon dust. The inside of the distributor block should 
be cleaned with a cloth moistened with gasoline and 
then wiped dry with a clean cloth. "When replacing the 
block, care must be exercised in pushing the carbon brush 
into the socket. Do not pull out the carbon brushes in the 
distributor because you think there is not enough tension 
on the small brass springs. In order to obtain the most 
efficient results, the normal setting of the spark-plug 
points should not exceed .025 of an inch, and it is ad- 
visable to have the gap just right before a spark-plug is 
inserted. 

The spark-plug electrodes may be easily set by means 
of the gauge attached to the screwdriver. The setting 
of the spark-plug points is an important function which 
is usually overlooked, ivith the result that the magneto 
is blamed ivhen it is not at fault. 

TIMING OF THE DIXIE MAGNETO 

In order to obtain the utmost efficiency from the en- 
gine, the magneto must be correctly timed to it. This 
operation is usually performed when the magneto is fitted 
to the engine at the factory. The correct setting may 
vary according to individuality of the engine, and some 



ie Magneto 




189 



•4-3 



-a 
s 
d 
o 
Pi 

s 

o 
o 



s 



a 


a 


t>o 


o 


cd 


3 




bn 


a> 


M 


X 


© 


n 


d 




bn 


o 


w 


rt 




o 


n 




o 


+-> 


tJ 


3 


a 


m 




•4J 


;>> 


a 


o 


o 




O 




bn 




g 








a 




3 





190 Aviat] 

engines may require an earlier^H^^Hp order to obtain 
the best results. However, shouE^^re occasion arise to 
retime the magneto, the procedure is as follows: Rotate 
the crank-shaft of the engine until one of the pistons, 
preferably that of cylinder No. 1, is % 6 of an inch ahead 
of the end of the compression stroke. With the timing 
lever in full retard position, the driving shaft of the 
magneto should be rotated in the. direction in which it 
will be driven. The circuit breaker should be closely 
observed and when the platinum contact points are about 
to separate, the drive gear or coupling should be secured 
to the drive shaft of the magneto. Care should be taken 
not to alter the position of the magneto shaft when 
tightening the nut to secure the gear or coupling, after 
which the magneto should be secured to its base. Ee- 
move the distributor block and determine which terminal 
of the block is in contact with the carbon brush of the 
distributor finger and connect with plug wire leading to 
No. 1 cylinder to this terminal. Connect the remaining 
plug wires in turn according to the proper sequence of 
firing of the cylinders. (See the wiring diagram for a 
typical six-cylinder engine at Fig. 70.) A terminal on 
the end of the cover spring of the magneto is provided 
for the purpose of connecting the wire leading to a ground 
switch for stopping the engine. 

A special model or type of magneto is made for 
V engines which use a compound distributor construc- 
tion instead of the simple type on the model illustrated 
and a different interior arrangement permits the pro- 
duction of four sparks per revolution of the rotors. This 
makes it possible to run the magneto slower than would 
be possible with the two-spark form. The application 
of two compound distributor magnetos of this type to a 
Thomas-Morse 135 horse-power motor of the eight-cylin- 
der V pattern is clearly shown at Fig. 71. 



93L{0j.im<? jj.oj.no ojauBto^f 




a 



DO 



191 



192 



Aviation Engines 



SPARK-PLUG DESIGN AND APPLICATION 

With the high-tension system of ignition the spark is 
produced by a current of high voltage jumping between 
two points which break the complete circuit, which would 
exist otherwise in the secondary coil and its external 
connections. The spark-plug is a simple device which 



Ah Starter 
Pipes 



Water Pump 




Ignition 
' Cables 



Compound 

. Distributor 

Magneto 



Wire 
Conduit 



-Ignition 
.' Cables 



Compound 
Distributor- 
Magneto 



Oil Pump 






Fig. 71. — How Magneto Ignition is Installed on Thomas-Morse 135 Horse- 
Power Motor. 



Spark-Plug Design and Application 



193 



consists of two terminal electrodes carried in a suitable 
shell member, which is screwed into the cylinder. Typical 
spark-plugs are shown in section at Fig. 72 and the 
construction can be easily understood. The secondary 
wire from the coil is attached to a terminal at the top 
of a central electrode member, which is supported in a 
bushing of some form of insulating material. The type 
shown at A employs a molded porcelain as an insulator, 
while that depicted at B uses a bushing of mica. The 




Scl/d Nlcktl ftod 




Fig. 72.— Spark -Plug Types Showing Construction and Arrangement 

of Parts. 

insulating bushing and electrode are housed in a steel 
body, which is provided with a screw thread at the bot- 
tom, by which means it is screwed into the combustion 
chamber. 

When porcelain is used as an insulating material it is 
kept from direct contact with the metal portion by some 
form of yielding packing, usually asbestos. This is nec- 
essary because the steel and porcelain have different 
coefficients of expansion and some flexibility must be 
provided at the joints to permit the materials to expand 
differently when heated. The steel body of the plug which 
is screwed into the cylinder is in metallic contact with it 
and carries sparking points which form one of the ter- 
minals of the air gap over which the spark occurs. The 



194 Aviation Engines 

current entering at the top of the ping cannot reach the 
ground, which is represented by the metal portion of the 
engine, until it has traversed the full length of the cen- 
tral electrode and overcome the resistance of the gap 
between it and the terminal point on the shell. The 
porcelain bushing is firmly seated against the asbestos 
packing by means of a brass screw gland which sets 
against a flange formed on the porcelain, and which 
screws into a thread at the upper portion of the plug 
body. 

The mica plug shown at B is somewhat simpler in 
construction than that shown at A. The mica core which 
keeps the central electrode separated from the steel body 
is composed of several layers of pure sheet mica wound 
around the steel rod longitudinally, and hundreds of 
stamped steel washers which are forced over this member 
and compacted under high pressure with some form of a 
binding material between them. Porcelain insulators are 
usually molded from high-grade clay and are approxi- 
mately of the shapes desired by the designers of the plug. 
The central electrode may be held in place by mechanical 
means such as nuts, packings, and a shoulder on the rod, 
as shown at A. Another method sometimes used is to 
cement the electrode in place by means of some form of 
fire-clay cement. Whatever method of fastening is used, 
it is imperative that the joints be absolutely tight so that 
no gas can escape at the time of explosion. Porcelain 
is the material most widely used because it can be glazed 
eo that it will not absorb oil, and it is subjected to such 
high temperature in baking that it is not liable to crack 
when heated. 

The spark-plugs may be screwed into any convenient 
part of the combustion chamber, the general practice 
being to install them in the caps over the inlet valves, 
or in the side of the combustion chamber, so the points 
will be directly in the path of the entering fresh gases 
from the carburetor. 

Other insulating materials sometimes used are glass, 



K 0( 



S lning of the lesi 9 n and Use 



195 



steatite (which i* A soapstone) and lava. Mica 

and porcelain are i- ^o common materials used because 
they give the best results. Glass is liable to crack, while 
lava or the soapstone insulating bushings absorb oil. 
The spark gap of the average plug is equal to about 
%2 of an inch for coil ignition and % of an inch when 
used in magneto circuits. A simple gauge for determi- 
ning the gap setting is the thickness of an ordinary visiting 




#8- 32 \y 
4mm.. 75 p.) 



'""**■{ 25 nfm. 
Across Flats 

16.9 Threads per inch : 1.5 millimeters pitch 
Root diameter 633 inch.: I6.09.mil/imeters 
Pitch diameter 678 ± inch : 17. 22+02millfmeters 
Outside diameter 7/7. inch •* 18. 2 millimeters 



Fig. 73. — Standard Airplane Engine Plug Suggested by S. A. E. Standards 

Committee. 



card for magneto plugs, or a space equal to the thickness 
of a worn dime for a coil plug. The insulating bushings 
are made in a number of different ways, and while de- 
tails of construction vary, spark-plugs do not differ essen- 
tially in design. The dimensions of the standardized plug 
recommended by the S. A. E. are shown at Fig. 73. 

It is often desirable to have a water-tight joint be- 
tween the high-tension cable and the terminal screw on 
top of the insulating bushing of the spark-plug, especially 
in marine applications. The plug shown at C, Fig. 72, 



196 Aviation Engines 

is provided with an insulating member or hood of porce- 
lain, which is secured by a clip in such a manner that it 
makes a water-tight connection. Should the porcelain 
of a conventional form of plug become covered with 
water or dirty oil, the high-tension current is apt to 
run down this conducting material on the porcelain and 
reach the ground without having to complete its circuit 
by jumping the air gap and producing a spark. It will 
be evident that wherever a plug is exposed to the ele- 
ments, which is often the case in airplane service, that it 
should be protected by an insulating hood which will keep 
the insulator dry and prevent short circuiting of the 
spark. The same end can be attained by slipping an 
ordinary rubber nipple over the porcelain insulator of 
any conventional plug and bringing up one end over the 
cable. 

TWO-SPARK IGNITION 

On most aviation engines, especially those having large 
cylinders, it is sometimes difficult to secure complete 
combustion by using a single-spark plug. If the com- 
bustion is not rapid the efficiency of the engine will be 
reduced proportionately. The compressed charge in the 
cylinder does not ignite all at once or instantaneously, 
as many assume, but it is the strata of gas nearest the 
plug which is ignited first. This in turn sets fire to 
consecutive layers of the charge until the entire mass 
is aflame. One may compare the combustion of gas in 
the gas-engine cylinder to the phenomenon which obtains 
when a heavy object is thrown into a pool of still water. 
First a small circle is seen at the point where the object 
has passed into the water, this circle in turn inducing 
other and larger circles until the whole surface of the 
pool has been agitated from the one central point. The 
method of igniting the gas is very similar, as the spark 
ignites the circle of gas immediately adjacent to the 
sparking point, and this circle in turn ignites a little 
larger one concentric with it. The second circle of flame 



Two-Spark Ignition 197 

sets fire to more of the gas, and finally the entire con- 
tents of the combustion chamber are burning. 

While ordinarily combustion is sufficiently rapid with 
a single plug so that the proper explosion is obtained at 
moderate engine speeds, if the engine is working fast and 
the cylinders are of large capacity more power may be 
obtained by setting fire to the mixture at two different 
points instead of but one. This may be accomplished by 
using two sparking-plugs in the cylinder instead of one, 
and experiments have shown that it is possible to gain 
from twenty-five to thirty per cent, in motor power at 
high speed with two-spark plugs, because the combustion 
of gas is accelerated by igniting the gas simultaneously 
in two places. The double-plug system on airplane en- 
gines is also a safeguard, as in event of failure of one 
plug in the cylinder the other would continue to fire the 
gas, and the engine will continue to function properly. 

In using magneto ignition some precautions are neces- 
sary relating to wiring and also the character of the spark- 
plugs employed. The conductor should be of good quality, 
have ample insulation, and be well protected from accu- 
mulations of oil, which would tend to decompose rubber 
insulation. It is customary to protect the wiring by run- 
ning it through the conduits of fiber or metal tubing lined 
with insulating material. Multiple strand cables should 
be used for both primary and secondary wiring, and the 
insulation should be of rubber at least %6 inch thick. 

The spark-plugs commonly used for battery and coil 
ignition cannot always be employed when a magneto is 
fitted. The current produced by the mechanical generator 
has a greater amperage and more heat value than that 
obtained from transformer coils excited by battery cur- 
rent. The greater heat may burn or fuse the slender 
points used on some battery plugs and heavier electrodes 
are needed to resist the heating effect of the more intense 
arc. While the current has greater amperage it is not of 
as high potential or voltage as that commonly produced 
by the secondary winding of an induction coil, and it 



198 



Aviation Engines 



cannot overcome as much of a gap. Manufacturers of 
magneto pings usually set the spark points about %4 of 
an inch apart. The most efficient magneto plug has a 
plurality of points so that when the distance between one 
set becomes too great the spark will take place between 




Pig, 74.. — Special Mica Plug for Aviation Engines. 

one of the other pairs of electrodes which are not sep- 
arated by so great an air space. 

SPECIAL PLUGS FOR AIRPLANE WORK 

Airplane work calls for special construction of spark- 
plugs, owing to the high compression used in the engines 
and the fact that they are operated on open throttle prac- 
tically all the time, thus causing a great deal of heat to 



Special Airplane Engine Plugs 199 

be developed. The plug shown at Fig. 74 was recently 
described in "The Automobile, ' ' and has been devised 
especially for airplane engines and automobile racing 
power plants. The core C is built up of mica washers, 
and has square shoulders. As mica washers of different 
sizes may be used, and accurate machining, such as is nec- 
essary with conical clamping surfaces, is not required, 
the plug can be produced economically. The square 
shoulders of the core afford two gasket seats, and when 
the core is clamped in the shell by means of check nut E, 
it is accurately centered and a tight joint is formed. This 
construction also makes a shorter plug than where coni- 
cal fits are used, thus improving the heat radiation through 
the stem. The lower end of the shell is provided with a 
baffle plate 0, which tends to keep the oil away from the 
mica. There are perforations L in this baffle plate to 
prevent burnt gases being pocketed behind the baffle plate 
and pre-igniting the new charge. This construction also 
brings the firing point out into the firing chamber of the 
engine, and has all the other advantages of a closed-end 
plug. The stem P is made of brass or copper, on account 
of their superior heat conductivity, and the electrode J 
is swedged into the bottom of the stem, as shown at K, 
in a secure manner. 

The shell is finned, as shown at G-, to provide greater 
heat radiating surface. There is also a fin F at the top 
of the stem, to increase the radiation of heat from the 
stem and electrode. The top of this finned portion is 
slightly countersunk, and the stem is riveted into same, 
thereby reducing the possibility of leakage past the 
threads on the stem. This finned portion is necked at A 
to take a slip terminal. 

In building up the core a small section of washers, I, 
is built up before the mica insulating tube D is placed on. 
This construction gives a better support to section I. 
Baffle plate is bored out to allow the electrode J to 
pass through, and the clearance between baffle plate and 
electrode is made larger than the width of the gap be- 



200 Aviation Engines 

tween the firing points, so that there is no danger of the 
spark jumping from the electrode to the baffle plate. 

This ping will be furnished either with or without the 
finned portion, to meet individual requirements. The 
manufacturers lay special stress upon the simplicity of 
construction and upon the method of clamping, which is 
claimed to make the plug absolutely gas-tight. 



CHAPTER Vn 

Why Lubrication Is Necessary — Friction Defined — Theory of Lubrica- 
tion — Derivation of Lubricants — Properties of Cylinder Oils — 
Factors Influencing Lubrication System Selection — Gnome Type 
Engines Use Castor Oil — Hall-Scott Lubrication System — Oil Sup- 
ply by Constant Level Splash System — Dry Crank-Case System Best 
for Airplane Engines — Why Cooling Systems Are Necessary — 
Cooling Systems Generally Applied — Cooling by Positive Pump 
Circulation — Thermo-Syphon System — Direct Air-Cooling Methods 
— Air-Cooled Engine Design Considerations. 

WHY LUBRICATION IS NECESSARY 

The importance of minimizing friction at the various 
bearing surfaces of machines to secure mechanical effi- 
ciency is fully recognized by all mechanics, and proper 
lubricity of all parts of the mechanism is a very essential 
factor upon which the durability and successful operation 
of the motor car power plant depends. All of the moving 
members of the engine which are in contact with other 
portions, whether the motion is continuous or intermit- 
tent, of high or low velocity, or of rectilinear or continued 
rotary nature, should be provided with an adequate sup- 
ply of oil. No other assemblage of mechanism is operated 
under conditions which are so much to its disadvantage 
as the motor car, and the tendency is toward a simplifica- 
tion of oiling methods so that the supply will be ample 
and automatically applied to the points needing it. 

In all machinery in motion the members which are in 
contact have a tendency to stick to each other, and the 
very minute projections which exist on even the smooth- 
est of surfaces would have a tendency to cling or adhere 
to each other if the surfaces were not kept apart by some 
elastic and unctuous substance. This will flow or spread 
out over the surfaces and smooth out the inequalities exist- 

201 



202 Aviation Engines 

ing which tend to produce heat and retard motion of the 
pieces relative to each other. 

A general impression which obtains is that well ma- 
chined surfaces are smooth, but while they are apparently 
free from roughness, and no projections are visible to the 
naked eye, any smooth bearing surface, even if very care- 
fully ground, will have a rough appearance if examined 
with a magnifying glass. An exaggerated condition to 
illustrate this point is shown at Fig. 75. The amount of 
friction will vary in proportion to the pressure on the 
surfaces in contact and will augment as the loads in- 
crease; the rougher surfaces will have more friction than 
smoother ones and soft bodies will produce more friction 
than hard substances. 

FRICTION DEFINED 

Friction is always present in any mechanism as a re- 
sisting force that tends to retard motion and bring all 
moving parts to a state of rest. The absorption of power 
by friction may be gauged by the amount of heat which 
exists at the bearing points. Friction of solids may be 
divided into two classes: sliding friction, such as exists 
between the piston and cylinder, or the bearings of a 
gas-engine, and rolling friction, which is that present 
when the load is supported by ball or roller bearings, or 
that which exists between the tires or the driving wheels 
and the road. Engineers endeavor to keep friction losses 
as low as possible, and much care is taken in all modern 
airplane engines to provide adequate methods of lubrica- 
tion, or anti-friction bearings at all points where con- 
siderable friction exists. 

THEORY OF LUBRICATION 

The reason a lubricant is supplied to bearing points 
will be easily understood if one considers that these 
elastic substances flow between the close fitting surfaces, 
and by filling up the minute depressions in the surfaces 
and covering the high spots act as a cushion which 



Theory of Lubrication 



203 



absorbs the beat generated and takes the wear instead 
of the metallic bearing surface. The closer the parts fit 
together the more fluid the lubricant must be to pass 
between their surfaces, and at the same time it must 
possess sufficient body so that it will not be entirely 
forced out by the pressure existing between the parts. 

Oils should have good adhesive, as well as cohesive, 
qualities. The former are necessary so that the oil film 



V/VX//, 



-Pillow Block 




Magnified 
Shaft 



Magnifying Glass 



Pig. 75. — Showing Use of Magnifying Glass to Demonstrate that Apparently 
Smooth Metal Surfaces May Have Minute Irregularities which Produce 
Friction. 

will cling well to the surfaces of the bearings; the latter, 
so the oil particles will cling together and resist the ten- 
dency to separation which exists all the time the bearings 
are in operation. When used for gas-engine lubrication 
the oil should be capable of withstanding considerable 
heat in order that it will not be vaporized by the hot por- 
tions of the cylinder. It should have sufficient cold test 
so that it will remain fluid and flow readily at low tem- 
perature. Lubricants should be free from acid, or alka- 



1 



204 Aviation Engines 



lies, which tend to produce a chemical action with metals 
and result in corrosion of the parts to which they are 
applied. It is imperative that the oil be exactly the 
proper quality and nature for the purpose intended and 
that it be applied in a positive manner. The requirements 
may be briefly summarized as follows: 

First — It must have sufficient body to prevent seizing 
of the parts to which it is applied and between which it 
is depended upon to maintain an elastic film, and yet it 
must not have too much viscosity, in order to minimize 
the internal or fluid friction which exists between the 
particles of the lubricant itself. 

Second — The lubricant must not coagulate or gum; 
must not injure the parts to which it is applied, either by 
chemical action or by producing injurious deposits, and 
it should not evaporate readily. 

Third — The character of the work will demand that 
the oil should not vaporize when heated or thicken to such 
a point that it will not flow readily when cold. 

Fourth — The oil must be free from acid, alkalies, ani- 
mal or vegetable fillers, or other injurious agencies. 

Fifth — It must be carefully selected for the work re- 
quired and should be a good conductor of heat. 

DERIVATION OF LUBRICANTS 

The first oils which were used for lubricating machin- 
ery were obtained from animal and vegetable sources, 
though at the present time most unguents are of mineral 
derivation. Lubricants may exist as fluids, semifluids, or 
solids. The viscosity will vary from light spindle or 
dynamo oils, which have but little more body than kero- 
sene, to the heaviest greases and tallows. The most com- 
mon solid employed as a lubricant is graphite, sometimes 
termed " plumbago " or " black lead." This substance is 
of mineral derivation. 

The disadvantage of oils of organic origin, such as 
those obtained from animal fats or vegetable substances, 
is that they will absorb oxygen from the atmosphere, 



Derivation of Lubricants 205 

which causes them to thicken or become rancid. Such 
oils have a very poor cold test, as they solidify at com- 
paratively high temperatures, and their flashing point is 
so low that they cannot be used at points where much 
heat exists. In most animal oils various acids are present 
in greater or less quantities, and for this reason they are 
not well adapted for lubricating metallic surfaces which 
may be raised high enough in temperature to cause de- 
composition of the oils. 

Lubricants derived from the crude petroleum are 
called "Oleonaphthas" and they are a product of the 
process of refining petroleum through which gasoline and 
kerosene are obtained. They are of lower cost than vege- 
table or animal oil, and as they are of non-organic origin, 
they do not become rancid or gummy by constant expo- 
sure to the air, and they will have no corrosive action 
on metals because they contain no deleterious substances 
in chemical composition. By the process of fractional 
distillation mineral oils of all grades can be obtained. 
They have a lower cold and higher flash test and there 
is not the liability of spontaneous combustion that exists 
with animal oils. 

The organic oils are derived from fatty substances, 
which are present in the bodies of all animals and in 
some portions of plants. The general method of extract- 
ing oil from animal bodies is by a rendering process, 
which consists of applying sufficient heat to liquefy the 
oil and then separating it from the tissue with which it 
is combined by compression. The only oil which is used 
to any extent in gas-engine lubrication that is not of 
mineral derivation is castor oil. This substance has been 
used on high-speed racing automobile engines and on 
airplane power plants. It is obtained from the seeds of 
the castor plant, which contain a large percentage of oil. 

Among the solid substances which may be used for 
lubricating purposes may be mentioned tallow, which is 
obtained from the fat of animals, and graphite and soap- 
stone, which are of mineral derivation. Tallow is never 



206 Aviation Engines 

used at points where it will be exposed to much heat, 
though it is often employed as a filler for greases used 
in transmission gearing of autos. Graphite is sometimes 
mixed with oil and applied to cylinder lubrication, though 
it is most often used in connection with greases in the 
landing gear parts and for coating wires and cables of 
the airplane. Graphite is not affected by heat, cold, acids, 
or alkalies, and has a strong attraction for metal surfaces. 
It mixes readily with oils and greases and increases their 
efficiency in many applications. It is sometimes used 
where it would not be possible to use other lubricants 
because of extremes of temperature. 

The oils used for cylinder lubrication are obtained 
almost exclusively from crude petroleum derived from 
American wells. Special care must be taken in the selec- 
tion of crude material, as every variety will not yield oil 
of the proper quality to be used as a cylinder lubricant. 
The crude petroleum is distilled as rapidly as possible 
with fire heat to vaporize off the naphthas and the burn- 
ing oils. After these vapors have been given off super- 
heated steam is provided to assist in distilling. When 
enough of the light elements have been eliminated the 
residue is drawn off, passed through a strainer to free 
it from grit and earthy matters, and is afterwards cooled 
to separate the wax from it. This is the dark cylinder oil 
and is the grade usually used for steam-engine cylinders. 

PROPERTIES OF CYLINDER OILS 

The oil that is to be used in the gasoline engine must 
be of high quality, and for that reason the best grades 
are distilled in a vacuum that the light distillates may be 
separated at much lower temperatures than ordinary 
conditions of distilling permit. If the degree of heat 
is not high the product is not so apt to decompose and 
deposit carbon. If it is desired to remove the color of 
the oil which is caused by free carbon and other impurities 
it can be accomplished by filtering the oil through char- 
coal. The greater the number of times the oil is filtered, 



Properties of Cylinder Oils 207 

the lighter it will become in color. The best cylinder 
oils have flash points usually in excess of 500 degrees F., 
and while they have a high degree of viscosity at 100 
degrees F. they become more fluid as the temperature 
increases. 

The lubricating oils obtained by refining crude petro- 
leum may be divided into three classes: 

First — The natural oils of great body which are pre- 
pared for use by allowing the crude material to settle 
in tanks at high temperature and from which the im- 
purities are removed by natural filtration. These oils are 
given the necessary body and are free from the volatile 
substances they contain by means of superheated steam 
which provides a source of heat. 

Second — Another grade of these natural oils which are 
filtered again at high temperatures and under pressure 
through beds of animal charcoal to improve their color. 

Third — Pale, limpid oils, obtained by distillation and 
subsequent chemical treatment from the residuum pro- 
duced in refining petroleum to obtain the fuel oils. 

Authorities agree that any form of mixed oil in which 
animal and mineral lubricants are combined should never 
be used in the cylinder of a gas engine as the admixture 
of the lubricants does not prevent the decomposition of 
the organic oil into the glycerides and fatty acids peculiar 
to the fat used. In a gas-engine cylinder the flame tends 
to produce more or less charring. The deposits of carbon 
will be much greater with animal oils than with those 
derived from the petroleum base because the constituents 
of a fat or tallow are not of the same volatile character 
as those which comprise the hydro-carbon oils which will 
evaporate or volatilize before they char in most instances. 

FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION 

The suitability of oil for the proper and efficient lubri- 
cation of all internal combustion engines is determined 
chiefly by the following factors: 



\ 



208 Aviation Engines 

1. Type of cooling system (operating temperatures). 

2. Type of lubricating system (method of applying 
oil to the moving parts). 

3. Eubbing speeds of contact surfaces. 

Were the operating temperatures, bearing surface 
speeds and lubrication systems identical, a single oil 
could be used in all engines with equal satisfaction. The 
only change then necessary in viscosity would be that due 
to climatic conditions. As engines are now designed, only 
three grades of oil are necessary for the lubrication of 
all types with the exception of Knight, air-cooled and 
some engines which run continuously at full load. In the 
specification of engine lubricants the feature of load 
carried by the engine should be carefully considered. 

Full Load Engines. 

1. Marine. 

2. Eacing automobile. 

3. Aviation. 

4. Farm tractor. 

5. Some stationary. 

Variable Load Engines. 

1. Pleasure automobile. 

2. Commercial vehicle. 

3. Motor cycle. 

4. Some stationary. 

Of the forms outlined, the only one we have any 
immediate concern about is the airplane power plant. 
The Piatt & Washburn Eefining Company, who have 
made a careful study of the lubrication problem as ap- 
plied to all types of engines, have found a peculiar set 
of conditions to apply to oiling high-speed constant-duty 
or " full-load " engines. Modern airplane engines are 
designed to operate continuously at a fairly uniform 
high rotative speed and at full load over long periods 
of time. As a sequence to this heavy duty the operating 



Lubricating Airplane Engines 209 

temperatures are elevated. For the sake of extreme light- 
ness in weight of all parts, very thin alloy steel aluminum 
or cast iron pistons are fitted and the temperature of 
the thin piston heads at the center reaches anywhere 
between 600° and 1,400° Fahr., as in automobile racing 
engines. Freely exposed to such intense heat hydro-carbon 
oils are partially "cracked" into light and heavy prod- 
ucts or polymerized into solid hydro-carbons. From these 
facts it follows that only heavy mineral oils of low carbon 
residue and of the greatest chemical purity and stability 
should be used to secure good lubrication. In all cases 
the oil should be sufficiently heavy to assure the highest 
horse-power and fuel and oil economy compatible with 
perfect lubrication, avoiding, at the same time, carbon- 
ization and ignition failure. "When aluminum pistons are 
used their superior heat-conducting properties aid mate- 
rially in reducing the rate of oil destruction. 

The extraordinary evolutions described by airplanes 
in flight make it a matter of vital necessity to operate 
engines inclined at all angles to the vertical as well as in 
an upside-down position. To meet this situation lubri- 
cating systems have been elaborated so as to deliver 
an abundance of oil where needed and to eliminate pos- 
sible flooding of cylinders. This is done by applying a 
full force feed system, distributing oil under considerable 
pressure to all working parts. Discharged through the 
bearings, the oil drains down to the suction side of a 
second pump located in the bottom of the base chamber. 
This pump being of greater capacity than the first pre- 
vents the accumulation of oil in the crank-case, and 
forces it to a separate oil reservoir-cooler, whence it 
flows back in rapid circulation to the pump feeding the 
bearings. With this arrangement positive lubrication 
is entirely independent of engine position. The lubri- 
cating system of the Thomas-Morse aviation engines, 
which is shown at Fig. 76, is typical of current practice. 



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210 



Gnome Type Engines Use Castor Oil 211 



GNOME TYPE ENGINES USE CASTOR OIL 

The construction and operation of rotative radial 
cylinder engines introduce additional difficulties of lubri- 
cation to those already referred to and merit especial 
attention. Owing to the peculiar alimentation systems 
of Gnome type engines, atomized gasoline mixed with 
air is drawn through the hollow stationary crank- shaft 
directly into the crank-case which it fills on the way to 
the cylinders. Therein lies the trouble. Hydrocarbon 
oils are soon dissolved by the gasoline and washed off, 
leaving the bearing surfaces without adequate protection 
and exposed to instant wear and destruction. So castor 
oil is resorted to as an indispensable but unfortunate 
compromise. Of vegetable origin, it leaves a much more 
bulky carbon deposit in the explosion chambers than 
does mineral oil and its great affinity for oxygen causes 
the formation of voluminous gummy deposit in the crank- 
case. Engines employing it need to be dismounted and 
thoroughly scraped out at frequent intervals. It is ad- 
visable to use only unblended chemically pure castor oil 
in rotative engines, first by virtue of its insolubility in 
gasoline and second because its extra heavy body can 
resist the high temperature of air-cooled cylinders. 

HALL-SCOTT LUBRICATION SYSTEM 

The oiling system of the Hall-Scott type A-5 125 
horse-power engine is clearly shown at Fig. 77. It is 
completely described in the instruction book issued by 
the company from which the following extracts are repro- 
duced by permission. Crank-shaft, connecting rods and 
all other parts within the crank-case and cylinders are 
lubricated directly or indirectly by a force-feed oiling 
system. The cylinder walls and wrist pins are lubricated 
by oil spray thrown from the lower end of connecting 
rod bearings. This system is used only upon A-5 engines. 
Upon A-7a and A-5a engines a small tube supplies oil 







<5 Cj ^ ^ 









too 






212 



Hall-Scott Lubricating System 213 

from connecting rod bearing directly upon the wrist pin. 
The oil is drawn from the strainer located at the lowest 
portion of the lower crank-case, forced around the main 
intake manifold oil jacket. From here it is circulated 
to the main distributing pipe located along the lower left 
hand side of upper crank-case. The oil is then forced 
directly to the lower side of crank-shaft, through holes 
drilled in each main bearing cup. Leakage from these 
main bearings is caught in scuppers placed upon the 
cheeks of the crank-shafts furnishing oil under pressure 
to the connecting rod bearings. A-7a and A-5a engines 
have small tubes leading from these bearings which con- 
vey the oil under pressure to the wrist pins. 

A bi-pass located at the front end of the distributing 
oil pipe can be regulated to lessen or raise the pressure. 
By screwing the valve in, the pressure will raise and 
more oil will be forced to the bearings. By unscrewing, 
pressure is reduced and less oil is fed. A-7a and A-5a 
engines have oil relief valves located just off of the main 
oil pump in the lower crank-case. This regulates the 
pressure at all times so that in cold weather there will 
be no danger of bursting oil pipes due to excessive pres- 
sure. If it is found the oil pressure is not maintained 
at a high enough level, inspect this valve. A stronger 
spring will not allow the oil to bi-pass so freely, and 
consequently the pressure will be raised; a weaker spring 
will bi-pass more oil and reduce the oil pressure mate- 
rially. Independent of the above-mentioned system, a 
small, directly driven rotary oiler feeds oil to the base 
of each individual cylinder. The supply of oil is fur- 
nished by the main oil pump located in the lower crank- 
case. A small sight-feed regulator is furnished to control 
the supply of oil from this oiler. This instrument should 
be placed higher than the auxiliary oil distributor itself 
to enable the oil to drain by gravity feed to the oiler. 
If there is no available place with the necessary height 
in the front seat of plane, connect it directly to the intake 
L fitting on the oiler in an upright position. It should 



214 Aviation Engines 

be regulated with full open throttle to maintain an oil 
level in the glass, approximately half way. 

An oil pressure gauge is provided. This should be run 
to the pilot's instrument board* The gauge registers the 
oil pressure upon the bearings, also determining its cir- 
culation. Strict watch should be maintained of this in- 
strument by pilot, and if for any reason its hand should 
drop to the motor should be immediately stopped and 
the trouble found before restarting engine. Care should 
be taken that the oil does not work up into the gauge, 
as it will prevent the correct gauge registering of oil 
pressure. The oil pressure will vary according to weather 
conditions and viscosity of oil used. In normal weather, 
with the engine properly warmed up, the pressure will 
register on the oil gauge from 5 to 10 pounds when the 
engine is turning from 1,275 to 1,300 r. p. m. This does 
not apply to all aviation engines, however, as the proper 
pressure advised for the Curtiss 0X2 motor is from 40 
to 55 pounds at the gauge. 

The oil sump plug is located at the lowest point of 
the lower crank-case. This is a combination dirt, water 
and sediment trap. It is easily removed by unscrewing. 
Oil is furnished mechanically to the cam-shaft housing 
under pressure through a small tube leading from the 
main distributing pipe at the propeller end of engine 
directly into the end of cam-shaft housing. The opposite 
end of this housing is amply relieved to allow the oil 
to rapidly flow down upon cam-shaft, magneto, pinion- 
shaft, and crank-shaft gears, after which it returns to 
lower crank-case. An outside overflow pipe is also pro- 
vided to carry away the surplus oil. 

DRAINING OIL FROM CRANK-CASE 

The oil strainer is placed at the lowest point of the 
lower crank-case. This strainer should be removed after 
every five to eight hours running of the engine and 
cleaned thoroughly with gasoline. It is also advisable 
to squirt distillate up into the case through the opening 



Hall-Scott Oiling System 215 

where the strainer has been removed. Allow this dis- 
tillate to drain out thoroughly before replacing the ping 
with strainer attached. Be sure gasket is in place on 
plug before replacing. Pour new oil in through either 
of the two breather pipes on exhaust side of motor. 
Be sure to replace strainer screens if removed. If, 
through oversight, the engine does not receive sufficient 
lubrication and begins to heat or pound, it should be 
stopped immediately. After allowing engine to cool pour 
at least three gallons of oil into oil sump. Fill radiator 
with water after engine has cooled. Should there be 
apparent damage, the engine should be thoroughly in- 
spected immediately without further running. If no ob- 
vious damage has been done, the engine should be given 
a careful examination at the earliest opportunity to see 
that the running without oil has not burned the bearings 
or caused other trouble. 

Oils best adapted for Hall- Scott engines have the fol- 
lowing properties: A flash test of not less than 400° F. ; 
viscosity of not less than 75 to 85 taken at 20° F. with 
Saybolt's Universal Viscosimeter. 

Zeroline heavy duty oil, manufactured by the Standard 
Oil Company of California; also, 

Gargoyle mobile B oil, manufactured by the Vacuum 
Oil Company, both fulfill the above specifications. One 
or the other of these oils can be obtained all over the 
world. 

Monogram extra heavy is also recommended. 

OIL SUPPLY BY CONSTANT LEVEL SPLASH SYSTEM 

The splash system of lubrication that depends on the 
connecting rod to distribute the lubricant is one of the 
most successful and simplest forms for simple four- and 
six-cylinder vertical automobile engines, but is not as 
well adapted to the oiling of airplane power plants for 
reasons previously stated. If too much oil is supplied 
the surplus will w r ork past the piston rings and into the 
combustion chamber, where it will burn and cause carbon 



216 Aviation Engines 

deposits. Too much oil will also cause an engine to smoke 
and an excess of lubricating oil is usually manifested 
by a bluish- white smoke issuing from the exhaust. 

A good method of maintaining a constant level of oil 
for the successful application of the splash system is 
shown at Fig. 78. The engine base casting includes a 
separate chamber which serves as an oil container and 
which is below the level of oil in the crank-case. The 
lubricant is drawn from the sump or oil container by 
means of a positive oil pump which discharges directly 
into the engine case. The level is maintained by an over- 
flow pipe which allows all excess lubricant to flow back 
into the oil container at the bottom of the cylinder. 
Before passing into the pump again the oil is strained 
or filtered by a screen of wire gauze and all foreign 
matter removed. Owing to the rapid circulation of the 
oil it may be used over and over again for quite a period 
of time. The oil is introduced directly into the crank- 
case by a breather pipe and the level is indicated by 
a rod carried by a float which rises when the container is 
replenished and falls when the available supply dimin- 
ishes. It will be noted that with such system the only 
apparatus required besides the oil tank which is cast 
integral with the bottom of the crank-case is a suitable 
pump to maintain circulation of oil. This member is 
always positively driven, either by means of shaft and 
universal coupling or direct gearing. As the system is 
entirely automatic in action, it will furnish a positive 
supply of oil at all desired points, and it cannot be 
tampered with by the inexpert because no adjustments 
are provided or needed. 

DRY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES 

In most airplane power plants it is considered desirable 
to supply the oil directly to the parts needing it by suit- 
able leads instead of depending solely upon the distrib- 
uting action of scoops on the connecting rod big ends. 
A system of this nature is shown at Fig. 77. The oil 



Best Oiling System for Airplane 



217 



is carried in the crank-case, as is common practice, but 
the normal oil level is below the point where it will be 
reached by the connecting rod. It is drawn from the 
crank-case by a plunger pump which directs it to a mani- 
fold leading directly to conductors which supply the main 



o 



Water Out/et 



/ntdke 
Pipe 



Exhaust 
P/pe 




Ft/ter/ng Screen 
Oif Out/et 



Geared O// Pu/7?p 



Fig. 78. — Sectional View of Typical Motor Showing Parts Needing Lubri- 
cation and Method of Applying Oil by Constant Level Splash System. 
Note also Water Jacket and Spaces for Water Circulation. 



218 



Aviation Engines 



journals. After the oil has been used on these points it 
drains back into the bottom of the crank-case. An excess 
is provided which is supplied to the connecting rod ends 
by passages drilled into the webs of the crank-shaft and 
part way into the crank-pins as shown by the dotted 
lines. The oil which is present at the connecting rod 









Main Feed. 


^^^^^N^T^xX 


Oil Strainer. 






Adjusting Valve. ^^ 


m^( 




Oil Filler. \ /C~\JSk 




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7^T)f ^s^kSw^r U% 


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j \ V) v^. 


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^^jixM^s^ 










^ /^ — Reservoir. 


r\ s*' iL f^f^^o r 












rj 








S-^g-Oil Pump. 



Fig. 79. — Pressure Feed Oil-Supply* System of Airplane Power Plants has 
Many Good Features. 

crank-pins is thrown off by centrifugal force and lubri- 
cates the cylinder walls and other internal parts. Regu- 
lating screws are provided so that the amount of oil 
supplied the different points may be regulated at will. 
A relief check valve is installed to take care of excess 
lubricant and to allow any oil that does not pass back 
into the pipe line to overflow or bi-pass into the main 
container. 

A simple system of this nature is shown graphically 
in a phantom view of the crank-case at Fig. 79, in which 



Why Cooling Systems Are Needed 219 

the oil passages are made specially prominent. The oil 
is taken from a reservoir at the bottom of the engine 
base by the usual form of gear oil pump and is supplied 
to a main feed manifold which extends the length of the 
crank-case. Individual conductors lead to the five main 
bearings, which in turn supply the crank-pins by pas- 
sages drilled through the crank-shaft web. In this power 
plant the connecting rods are hollow section bronze 
castings and the passage through the center of the con- 
necting rod serves to convey the lubricant from the 
crank-pins to the wrist-pins. The cylinder walls are oiled 
by the spray of lubricant thrown off the revolving crank- 
shaft by centrifugal force. Oil projection by the dippers 
on the connecting rod ends from constant level troughs 
is unequal upon the cylinder walls of the two-cylinder 
blocks of an eight- or twelve-cylinder V engine. This 
gives rise, on one side of the engine, to under-lubrication, 
and, on the other side, to over-lubrication, as shown at 
Fig. 80, A. This applies to all modifications of splash 
lubricating systems. 

When a force-feed lubricating system is used, the oil, 
escaping past the cheeks of both ends of the crank-pin 
bearings, is thrown off at a tangent to the crank-pin 
circle in all directions, supplying the cylinders on both 
sides with an equal quantity of oil, as at Fig. 80, B. 

WHY COOLING SYSTEMS ARE NECESSARY 

The reader should understand from preceding chap- 
ters that the power of an internal-combustion motor is 
obtained by the rapid combustion and consequent ex- 
pansion of some inflammable gas. The operation in 
brief is that when air or any other gas or vapor is 
heated, it will expand and that if this gas is confined 
in a space which will not permit expansion, pressure will 
be exerted against all sides of the containing chamber. 
The more a gas is heated,- the more- pressure it will 
exert upon the walls of the combustion chamber it 






220 



Aviation Engines 




Fig. 80 Why Pressure Feed System is Best for Eight-Cylinder Vee 

Airplane Engines. 



Why Cooling Systems are Needed 221 

confines. Pressure in a gas may be created by increasing 
its temperature and inversely heat may be created by 
pressure. When a gas is compressed its total volume is 
reduced and the temperature is augmented. 

The efficiency of any form of heat engine is deter- 
mined by the power obtained from a certain fuel con- 
sumption. A definite amount of energy will be liberated 
in the form of heat when a pound of any fuel is burned. 
The efficiency of any heat engine is proportional to the 
power developed from a definite quantity of fuel with the 
least loss of thermal units. If the greater proportion 
of the heat units derived by burning the explosive mix- 
ture could be utilized in doing useful work, the efficiency 
of the gasoline engine would be greater than that of 
any other form of energizing power. There is a great 
loss of heat from various causes, among which can be 
cited the reduction of pressure through cooling the motor 
and the loss of heat through the exhaust valves when 
the burned gases are expelled from the cylinder. 

The loss through the water jacket of the average auto- 
mobile power plant is over 50 per cent, of the total fuel 
efficiency. This means that more than half of the heat 
units available for power are absorbed and dissipated 
by the cooling water. Another 16 per cent, is lost through 
the exhaust valve, and but 33% per cent, of the heat 
units do useful work. The great loss of heat through 
the cooling systems cannot be avoided, as some method 
must be provided to keep the temperature of the engine 
within proper bounds. It is apparent that the rapid 
combustion and continued series of explosions would 
soon heat the metal portions of the engine to a red heat 
if some means were not taken to conduct much of this 
heat away. The high temperature of the parts would 
burn the lubricating oil, even that of the best quality, 
and the piston and rings would expand to such a degree, 
especially when deprived of oil, that they would seize in 
the cylinder. This would score the walls, and the friction 
which ensued would tend to bind the parts so tightly 



222 



Aviation Engines 



that the piston would stick, bearings would be burned 
out, the valves would warp, and the engine would soon 
become inoperative. 

The best temperature to secure efficient operation is 
one on which considerable difference of opinion exists 
among engineers. The fact that the efficiency of an 
engine is dependent upon the ratio of heat converted 



Cylinder Walls 
180° h 350° Fahr. 



Heat of Explosion 2000° to 3000° Fahr. 



.Piston Heads 
300° to 1000° Fahr. 



Piston Walls 
200°to400°Fahr 




Crank Bearing Oil 
140 n t 250° Fahr ,>■ 



Sump Oil SO to 200 "Fahr.- 



Fig. 81. — Operating Temperatures of Automobile Engine Parts Useful as a 
Guide to Understand Airplane Power Plant Heat. 



into useful work compared to that generated by the 
explosion of the gas is an accepted fact. It is very 
important that the engine should not get too hot, and 
on the other hand it is equally vital that the cylinders, 
be not robbed of too much heat. The object of cylinder 
cooling is to keep the temperature of the cylinder below 
the danger point, but at the same time to have it as 
high as possible to secure maximum power from the 
gas burned. The usual operating temperatures of an 



Cooling Systems Generally Applied 223 

automobile engine are shown at Fig. 81, and this can 
be taken as an approximation of the temperatures apt to 
exist in an airplane engine of conventional design as well 
when at ground level or not very high in the air. The 
newer very high compression airplane engines in which 
compressions of eight or nine atmospheres are used, or 
about 125 pounds per square inch, will run considerably 
hotter than the temperatures indicated. 



COOLING SYSTEMS GENERALLY APPLIED 

There are two general systems of engine cooling in 
common use, that in which water is heated, by the ab- 
sorption of heat from the engine and then cooled by air, 
and the other method in which the air is directed onto 
the cylinder and absorbs the heat directly instead of 
through the medium of water. When the liquid is em- 
ployed in cooling it is circulated through jackets which 
surround the cylinder casting and the water may be 
kept in motion by two methods. The one generally 
favored is to use a positive circulating pump of some 
form which is driven by the engine to keep the water 
in motion. The other system is to utilize a natural 
principle that heated water is lighter than cold liquid 
and that it will tend to rise to the top of the cylinder 
when it becomes heated to the proper temperature and 
cooled water takes its place at the bottom of the water 
jacket. 

Air-cooling methods may be by radiation or convec- 
tion. In the former case the effective outer surface of 
the cylinder is increased by the addition of flanges 
machined or cast thereon, and the air is depended on 
to rise from the cylinder as heated and be replaced by 
cooler air. This, of course, is found only on stationary 
engines. When a positive air draught is directed against 
the cylinder by means of the propeller slip stream in 
an airplane, cooling is by convection and radiation both. 
Sometimes the air draught may be directed against the 



224 



Aviation Engines 



cylinder walls by some form of jacket which confines it 
to the heated portions of the cylinder. 

COOLING BY POSITIVE WATER CIRCULATION 

A typical water-cooling system in which a pump is 
depended upon to promote circulation of the cooling 
liquid is shown at Figs. 82 and 83. The radiator is car- 
ried at the front end of the fuselage in most cases, and 
serves as a combined water tank and cooler, but in some 
cases it is carried at the side of the engine, as in Fig. 



.Outlet Pipes for Hot Water 



Filler Cap --.„ 




Centrifugal- 
Pump 



'Centrifugal 
Pump 



Fig. 82. — Water Cooling of Salmson Seven-Cylinder Radial Airplane Engine. 

84, or attached to the central portion of the aerofoil or 
wing structure. It is composed of an upper and lower 
portion joined together by a series of pipes which may 
be round and provided with a series of fins to radiate 
the heat, or which may be flat in order to have the water 
pass through in thin sheets and cool it more easily. 
Cellular or honeycomb coolers are composed of a large 
number of bent tubes which will expose a large area of 
surface to the cooling influence of the air draught forced 
through the radiator either by the forward movement 
of the vehicle or by some type of fan. The cellular and 



Cooling by Positive Circulation 



225 



flat tube types have almost entirely displaced the flange 
tube radiators which were formerly popular because they 
cool the water more effectively, and may be made lighter 
than the tubular radiator could be for engines of the 
same capacity. 

The water is drawn from the lower header of the 
radiator by the pump and is forced through a manifold 



f Mr-Tractor Screw - 

Radiator, 
' Filler Cap ' j Hose for 



1 \ Flexible Connection A / . Ill \ 7 



i \ e. 




g Pipe; from 
Water Jacket 
to Pump 



Pipe frpm 
Bottom of 
Radiator*to 
Water Pump 



& 



.ongerons^ 
Engine Bed 



Pig. 83. — How Water Cooling System of Thomas Airplane Engine is 
Installed in Fuselage. 

to the lower portion of the water jackets of the cylinder. 
It becomes heated as it passes around the cylinder walls 
and combustion chambers and the hot water passes out 
of the top of the water jacket to the upper portion of 
the radiator. Here it is divided in thin streams and 
directed against comparatively cool metal which abstracts 
the heat from the water. As it becomes cooler it falls 
to the bottom of the radiator because its weight increases 
as the temperature becomes lower. By the time it reaches 



226 



Aviation Engines 



the lower tank of the radiator it has been cooled suffi- 
ciently so that it may be again passed aronnd the cylin- 
ders of the motor. The popular form of circulating 
pump is known as the "centrifugal type" because a rotary 
impeller of paddle-wheel form throws water which it 
receives at a central point toward the outside and thus 
causes it to maintain a definite rate of circulation. The 
pump is always a separate appliance attached to the 



Upper Tank 




\ Propeller ■ 

Cold Water 
Pipe 



Fig. 84. — Finned Tube Radiators at the Side of Hall-Scott Airplane Power 
Plant Installed in Standard Fuselage. 



engine and driven by positive gearing or direct- shaft 
connection. The centrifugal pump is not as positive as 
the gear form, and some manufacturers prefer the latter 
because of the positive pumping features. They are 
very simple in form, consisting of a suitable cast body 
in which a pair of spur pinions having large teeth are 
carried. One of these gears is driven by suitable means, 
and as it turns the other member they maintain a flow 
of water around the pump body. The pump should al- 
ways be installed in series with the water pipe which 



Water Circulation by Natural System 227 

conveys the cool liquid from the lower compartment of the 
radiator to the coolest portion of the water jacket. 

WATER CIRCULATION BY NATURAL SYSTEM 

Some automobile engineers contend that the rapid 
water circulation obtained by using a pump may cool 
the cylinders too much, and that the temperature of the 
engine may be reduced so much that the efficiency will 
be lessened. For this reason there is a growing tendency 
to use the natural method of water circulation as the 
cooling liquid is supplied to the cylinder jackets just 
below the boiling point, and the water issues from the 
jacket at the top of the cylinder after it has absorbed 
sufficient heat to raise it just about to the boiling point. 

As the water becomes heated by contact with the hot 
cylinder and combustion-chamber walls it rises to the top 
of the water jacket, flows to the cooler, where enough 
of the heat is absorbed to cause it to become sensibly 
greater in" weight. As the water becomes cooler, it falls 
to the bottom of the radiator and it is again supplied 
to the water jacket. The circulation is entirely automatic 
and continues as long as there is a difference in tem- 
perature between the liquid in the water spaces of the 
engine and that in the cooler. The circulation becomes 
brisker as the engine becomes hotter and thus the tem- 
perature of the cylinders is kept more nearly to a fixed 
point. "With the thermosyphon system the cooling liquid 
is nearly always at its boiling point, whereas if the cir- 
culation is maintained by a pump the engine will become 
cooler at high speed and will heat up more at low speed. 

"With the thermosyphon, or natural system of cooling, 
more water must be carried than with the pump-main- 
tained circulation methods. The water spaces around 
the cylinders should be larger, the inlet and discharge 
water manifolds should have greater capacity, and be 
free from sharp corners which might impede the flow. 
The radiator must also carry more water than the form 
used in connection with the pump because of the brisker 



228 Aviation Engines 

pump circulation which maintains the engine temperature 
at a lower point. Consideration of the above will show 
why the pump system is almost universally used in 
connection with airplane power plant cooling. 

DIRECT AIR-COOLING METHODS 

The earliest known method of cooling the cylinder 
of gas-engines was by means of a current of air passed 
through a jacket which confined it close to the cylinder 
walls and was used by Daimler on his first gas-engine. 
The gasoline engine of that time was not as efficient as 
the later form, and other conditions which materialized 
made it desirable to cool the engine by water. Even as 
gasoline engines became more and more perfected there 
has always existed a prejudice against air cooling, though 
many forms of engines have been used, both in automo- 
bile and aircraft applications where the air-cooling method 
lias proven to be very practical. 

The simplest system of air cooling is that in which 
the cylinders are provided with a series of flanges which 
increase the effective radiating surface of the cylinder 
and directing an air current from a fan against the 
flanges to absorb the heat. This increase in the avail- 
able radiating surface of an air-cooled cylinder is neces- 
sary because air does not absorb heat as readily as water 
and therefore more surface must be provided that the 
excess heat be absorbed sufficiently fast to prevent dis- 
tortion of the cylinders. Air-cooling systems are based 
on a law formulated by Newton, which is: "The rate for 
cooling for a body in a uniform current of air is directly 
proportional to the speed of the air current and the 
amount of radiating surface exposed to the cooling 
effect.'* 

AIR-COOLED ENGINE DESIGN CONSIDERATIONS 

There are certain considerations which must be taken 
into account in designing an air-cooled engine, which are 
often overlooked in those forms cooled by water. Large 



Air-Cooled Engines 



229 



valves must be provided to insure rapid expulsion of 
the flaming exhaust gas and also to admit promptly the 
fresh cool mixture from the carburetor. The valves of 
air-cooled engines are usually placed in the cylinder- 



'l^Jracfo r $c re w 
/ : ./A i r Cooled Flan ged Cyiin d e .> 




Fig. 85. — Anzani Testing His Five-Cylinder Air Cooled Aviation Motor 
Installed in Bleriot Monoplane. Note Exposure of Flanged Cylinders 
to Propeller Slip Stream. 



head, in order to eliminate any pockets or sharp passages 
which would impede the flow of gas or retain some of 
the products of combustion and their heat. When high 
power is desired multiple-cylinder engines should be used, 
as there is a certain limit to the size of a successful 



230 Aviation Engines 

air-cooled cylinder. Much better results are secured from 
those having small cubical contents because the heat from 
small quantities of gas will be more quickly carried off 
than from greater amounts. All successful engines of 
the aviation type which have been air-cooled have been 
of the multiple-cylinder type. 

An air-cooled engine must be placed in ;the fuselage, 
as at Fig. 85, in such a 'way that there will be a positive 
circulation of air around it all the time that it is in 
operation. The air current may be produced by the 
tractor screw at the front end of the motor, or by a 
suction or blower fan attached to the crank-shaft as in the 
Renault engine or by rotating the cylinders as in the 
Le Rhone and Gnome motors. Greater care is required 
in lubrication of the air-cooled cylinders and only the best 
quality of oil should be used to insure satisfactory oiling. 

The combustion chambers must be proportioned so 
that distribution of metal is as uniform as possible in 
order to prevent uneven expansion during increase in 
temperature and uneven contraction when the cylinder 
is cooled. It is essential that the inside walls of the 
combustion chamber be as smooth as possible because 
any sharp angle or projection may absorb sufficient heat 
to remain incandescent and cause trouble by igniting the 
mixture before the proper time. The best grades of cast 
iron or steel should be used in the cylinder and piston 
and the machine work must be done very accurately 
so the piston will operate with minimum friction in the 
cylinder. The cylinder bore should not exceed 4% or 5 
inches and the compression pressure should never exceed 
75 pounds absolute, or about five atmospheres, or serious 
overheating will result. 

As an example of the care taken in disposing of the 
exhaust gases in order to obtain practical air-cooling, 
some cylinders are provided with a series of auxiliary 
exhaust ports uncovered by the piston when it reaches 
the end of its power stroke. The auxiliary exhaust ports 
open just as soon as the full force of the explosion has 



Air-Cooling Methods 231 

been spent and a portion of the flaming gases is dis- 
charged throngh the ports in the bottom of the cylinder. 
Less of the exhanst gases remains to be discharged 
through the regular exhanst member in the cylinder-head 
and this will not heat the walls of the cylinder nearly 
as much as the larger quantity of hot gas would. That 
the auxiliary exhaust port is of considerable value is 
conceded by many designers of fixed and fan-shaped air- 
cooled motors for airplanes. 

Among the advantages stated for direct air cooling, 
the greatest is the elimination of cooling water and its 
cooling auxiliaries, which is a factor of some moment, 
as it permits considerable reduction in horse-power-weight 
ratio of the engine, something very much to be desired. 
In the temperate zone, where the majority of airplanes 
are used, the weather conditions change in a very few 
months from the warm summer to the extreme cold 
winter, and when water-cooled systems are employed it is 
necessary to add some chemical substance to the water 
to prevent it from freezing. The substances commonly 
employed are glycerine, wood alcohol, or a saturated 
solution of calcium chloride. Alcohol has the disadvan- 
tage in that it vaporizes readily and must be often re- 
newed. Glycerine affects the rubber hose, while the 
calcium chloride solution crystallizes and deposits salt 
in the radiator and water pipes. 

One of the disadvantages of an air-cooling method, 
as stated by those who do not favor this system, is that 
engines cooled by air cannot be operated for extended 
periods under constant load or at very high speed with- 
out heating up to such a point that premature ignition 
of the charge may result. The water-cooling systems, 
at the other hand, maintain the temperature of the engine 
more nearly constant than is possible with an air-cooled 
motor, and an engine cooled by water can be operated 
under conditions of inferior lubrication or poor mixture 
adjustment that would seriously interfere with proper 
and efficient cooling by air. 



232 Aviation Engines 

Air-cooled motors, as a rule, use less fuel than water- 
cooled engines, because the higher temperature of the 
cylinder does not permit of a full charge of gas being 
inspired on the intake stroke. As special care is needed 
in operating an air-cooled engine to obtain satisfactory 
results and because of the greater difficulty which obtains 
in providing proper lubrication and fuel mixturers which 
will not produce undue heating, the air-cooled system 
has but few adherents at the present time, and practically 
all airplanes, with but very few exceptions, are provided 
with water-cooled power plants. Those fitted with air- 
cooled engines are usually short-flight types where maxi- 
mum lightness is desired in order to obtain high speed 
and quick climb. The water-cooled engines are best 
suited for airplanes intended for long flights. The Gnome, 
Le Ehone and Cterget engines are thoroughly practical 
and have been widely used in France and England. 
These are rotary radial cylinder types. The Anzani is 
a fixed cylinder engine used on training machines, while 
the Eenault is a V-type engine made in eight- and twelve- 
cylinder V forms that has been used on reconnaissance 
and bombing airplanes with success. These types will 
be fully considered in proper sequence. 



CHAPTER VIII 

Methods of Cylinder Construction — Block Castings — Influence on 
Crank-Shaft Design — Combustion Chamber Design — Bore and 
Stroke Ratio — Meaning of Piston Speed — Advantage of Off-Set 
Cylinders — Valve Location of Vital Import — Valve Installation 
Practice — Valve Design and Construction — Valve Operation — 
Methods of Driving Cam-Shaft — Valve Springs — Valve Timing — 
Blowing Back — Lead Given Exhaust Valve — Exhaust Closing, 
Inlet Opening — Closing the Inlet Valve — Time of Ignition — How 
an Engine Is Timed — Gnome "Monosoupape" Valve Timing — 
Springless Valves — Four Valves per Cylinder. 

The improvements noted in the modern internal com- 
bustion motors have been due to many conditions. The 
continual experimenting by leading mechanical minds 
could have but one ultimate result. The parts of the 
engines have been lightened and strengthened, and greater 
power has been obtained without increasing piston dis- 
placement. A careful study has been made of the many 
conditions which make for efficient motor action, and 
that the main principles are well recognized by all en- 
gineers is well shown by the standardization of design 
noted in modern power plants. There are many different 
methods of applying the same principle, and it will be 
the purpose of this chapter to define the ways in which 
the construction may be changed and still achieve the 
same results. The various components may exist in many 
different forms, and all have their advantages and dis- 
advantages. That all methods are practical is best shown 
by the large number of successful engines which use 
radically different designs. 

METHODS OF CYLINDER CONSTRUCTION 

One of the most important parts of the gasoline 
engine and one that has material bearing upon its effi- 
ciency is the cylinder unit. The cylinders may be cast 

233 



234 Aviation Engines 

individually, or in pairs, and it is possible to make all 
cylinders a unit or block casting. Some typical methods 
of cylinder construction are shown in accompanying illus- 
trations. The appearance of individual cylinder castings 
may be ascertained by examination of the Hall-Scott 
airplane engine. Air-cooled engine cylinders are always 
of the individual pattern. 

Considered from a purely theoretical point of view, 
the individual cylinder casting has much in its favor. 
It is advanced that more uniform cooling is possible 
than where the cylinders are cast either in pairs or three 
or four in one casting. More uniform cooling insures 
that the expansion or change of form due to heating will 
be more equal. This is an important condition because 
the cylinder bore must remain true under all conditions 
of operation. If the heating effect is not uniform, which 
condition is liable to obtain if metal is not evenly dis- 
tributed, the cylinder may become distorted by heat and 
the bore be out of truth. When separate cylinders are 
used it is possible to make a uniform water space and 
have the cooling liquid evenly distributed around the 
cylinder. In multiple cylinder castings this is not always 
the rule, as in many instances, especially in four-cylinder 
block motors where compactness is the main feature, there 
is but little space between the cylinders for the passage 
of water. Under such circumstances the cooling effect 
is not even, and the stresses which obtain because of 
unequal expansion may distort the cylinder to some 
extent. When steel cylinders are made from forgings, 
the water jackets are usually of copper or sheet steel 
attached to the forging by autogenous welding; in the 
case of the latter and, in some cases, the former may be 
electro-deposited on the cylinders. 

BLOCK CASTINGS 

The advantage of casting the cylinders in blocks is 
that a motor may be much shorter than it would be if 
individual castings were used. It is admitted that when 



Block Casting of Cylinders 



235 



the cylinders are cast together a more compact, rigid, 
and stronger power plant is obtained than when cast 
separately. There is a disadvantage, however, in that 
if one cylinder becomes damaged it will be necessary to 




ffS© QB S© SB 



:o) (sPlo) (o) ^ (o); (of~%) © 



UfE3_i=3 



Viewed from Top 



oo'oo/ooao 



o e e o 



o o o 



e o 



OOP 




Side View 



Fig. 86. — Views of Four-Cylinder Duesenberg Airplane Engine 
Cylinder Block. 

replace the entire unit, which means scrapping three 
good cylinders because one of the four has failed. When 
the cylinders are cast separately one need only replace 
the one that has become damaged. The casting of four 
cylinders in one unit is made possible by improved 



236 Aviation Engines 

foundry methods, and when proper provision is made for 
holding the cores when the metal is poured and the 
cylinder casts are good, the construction is one of dis- 
tinct merit. It is sometimes the case that the proportion 
of sound castings is less when cylinders are cast in 
block, but if the proper precautions are observed in 
molding and the proper mixtures of cast iron used, the 
ratio of defective castings is no more than when cylinders 
are molded individually. As an example of the courage 
of engineers in departing from old-established rules, the 
cylinder casting shown at Fig. 86 may be considered 
typical. This is used on the Duesenberg four-cylinder 
sixteen-valve 4%" x 7" engine which has a piston dis- 
placement of 496 cu. in. At a speed of 2,000 r.p.m., 
corresponding to a piston speed of 2,325 ft. per min., the 
engine is guaranteed to develop 125 horse-power. The 
weight of the model engine without gear reduction is 
436 lbs., but a number of refinements have been made in 
the design whereby it is expected to get the weight down 
to 390 lbs. The four cylinders are cast from semi-steel 
in a single block, with integral heads. The cylinder 
construction is the same as that which has always 
been used by Mr. Duesenberg, inlet and exhaust valves 
being arranged horizontally opposite each other in the 
head. There are large openings in the water jacket 
at both sides and at the ends, which are closed by means 
of aluminum covers, water-tightness being secured by 
the use of gaskets. This results in a saving in weight 
because the aluminum covers can be made considerably 
lighter than it would be possible to cast the jacket walls, 
and, besides, it permits of obtaining a more nearly uni- 
form thickness of cylinder wall, as the cores can be 
much better supported. The cooling water passes com- 
pletely around each cylinder, and there is a very con- 
siderable space between the two central cylinders, this 
being made necessary in order to get the large bearing 
area desirable for the central bearing. 

It is common practice to cast the water jackets inte- 



Advantage of Block Castings 237 

gral with the cylinders, if cast iron or aluminum is used, 
and this is also the most economical method of applying 
it because it gives good results in practice. An important 
detail is that the water spaces must be proportioned so 
that they are equal around the cylinders whether these 
members are cast individually, in pairs, threes or fours. 
When cylinders are cast in block form it is good practice 
to leave a large opening in the jacket wall which will 
assist in supporting the core and make for uniform water 
space. It will be noticed that the casting shown at Fig. 
86 has a large opening in the side of the cylinder block. 
These openings are closed after the interior of the casting 
is thoroughly cleaned of all sand, core wire, etc., by brass, 
cast iron or aluminum plates. These also have particular 
value in that they may be removed after the motor has 
been in use, thus permitting one to clean out the interior 
of the water jacket and dispose of the rust, sediment, 
and incrustation which are always present after the 
engine has been in active service for a time. 

Among the advantages claimed for the practice of 
casting cylinders in blocks may be mentioned compact- 
ness, lightness, rigidity, simplicity of water piping, as well 
as permitting the use of simple forms of inlet and exhaust 
manifolds. The light weight is not only due to the reduc- 
tion of the cylinder mass but because the block construc- 
tion permits one to lighten the entire motor. The fact 
that all cylinders are cast together decreases vibration, 
and as the construction is very rigid, disalignment of 
working parts is practically eliminated. When inlet and 
exhaust manifolds are cored in the block casting, as is 
sometimes the case, but one joint is needed on each of 
these instead of the multiplicity of joints which obtain 
when the cylinders are individual castings. The water 
piping is also simplified. In the case of a four-cylinder 
block motor but two pipes are used; one for the water 
to enter the cylinder jacket, the other for the cooling 
liquid to discharge through. 



238 



Aviation Engines 



INFLUENCE ON CRANK-SHAFT DESIGN 

The method of casting the cylinders has a material 
influence on the design of the crank- shaft as will be shown 
in proper sequence. When four cylinders are combined 
in one block it is possible to use a two-bearing crank-shaft. 
Where cylinders are cast in pairs a three-bearing crank- 
shaft is commonly supplied, and when cylinders are cast 




Copper Asbestos Gasket 




^•Cylinder Liper 

Aluminum Cylinder 
Pair Casting 



.Cylinder 
Head 




Fig. 87. — Twin-Cylinder Block of Sturtevant Airplane Engine is Cast of 
Aluminum, and Has Removable Cylinder Head. 

as individual units it is thought necessary to supply a 
five-bearing crank-shaft, though sometimes shafts having 
but three journals are used successfully. Obviously the 
shafts must be stronger and stiffer to withstand the 
stresses imposed if two supporting bearings are used 
than if a larger number are employed. In this connec- 
tion it may be stated that there is less difficulty in secur- 
ing alignment with a lesser number of bearings and there 
is also less friction. On the other hand, the greater the 
number of points of support a crank-shaft has the lighter 
the webs can be made and still have requisite strength. 



Combustion Chamber Design 



239 



COMBUSTION CHAMBER DESIGX 

Another point of importance in the design of the cylin- 
der, and one "which has considerable influence upon the 
power developed, is the shape of the combustion chamber. 
The endeavor of designers is to obtain maximum power 
from a cylinder of certain proportions, and the greater 
energy obtained without increasing piston displacement 
or fuel consumption the higher the efficiency of the motor. 
To prevent troubles due to pre-ignition it is necessary 




Fig. 88. — Aluminum Cylinder Pair Casting of Thomas 150 Horse-Power 
Airplane Engine is of the L Head Type. 

that the combustion chamber be made so that there will 
be no roughness, sharp corners, or edges of metal which 
may remain incandescent when heated or which will serve 
to collect carbon deposits by providing a point of anchor- 
age. With the object of providing an absolutely clean 
combustion chamber some makers use a separable head 
unit to their twin cylinder castings, such as shown at 
Fig. 87 and Fig. 88. These permit one to machine the 
entire interior of the cylinder and combustion chamber. 
The relation of valve location and combustion chamber 
design will be considered in proper sequence. These 
cylinders are cast of aluminum, instead of cast iron, as 



240 Aviation Engines 

is customary, and are provided with steel or cast iron 
cylinder liners forced in the soft metal casting bores. 

BORE AND STROKE RATIO 

A question that has been a vexed one and which has 
been the subject of considerable controversy is the proper 
proportion of the bore to the stroke. The early gas en- 
gines had a certain well-defined bore to stroke ratio, as 
it was usual at that time to make the stroke twice as long 
as the bore was wide, but this cannot be done when high 
speed is desired. With the development of the present- 
day motor the stroke or piston travel has been gradually 
shortened so that the relative proportions of bore and 
stroke have become nearly equal. Of late there seems to 
be a tendency among designers to return to the propor- 
tions which formerly obtained, and the stroke is some- 
times one and a half or one and three-quarter times the 
bore. 

Engines designed for high speed should have the stroke 
not much longer than the diameter of the bore. The dis- 
advantage of short-stroke engines is that they will not 
pull well at low speeds, though they run with great regu- 
larity and smoothness at high velocity. The long-stroke 
engine is much superior for slow speed work, and it will 
pull steadily and with increasing power at low speed. 
It was formerly thought that such engines should never 
turn more than a moderate number of revolutions, in 
order not to exceed the safe piston speed of 1.000 feet 
per minute. This old theory or rule of practice has been 
discarded in designing high efficiency automobile racing 
and aviation engines, and piston speeds from 2,500 to 
3,000 feet per minute are sometimes used, though the 
average is around 2,000 feet per minute. While both 
short- and long-stroke motors have their advantages, it 
would seem desirable to average between the two. That 
is why a proportion of four to five or six seems to be 
more general than that of four to seven or eight, which 
would be a long-stroke ratio. Careful analysis of a num- 



Meaning of Piston Speed 241 

ber of foreign aviation motors shows that the average 
stroke is abont 1.2 times the bore dimensions, thongh 
some instances were noted where it was as high as 1.7 
times the bore. 

MEANING OF PISTON SPEED 

The factor which limits the stroke and makes the 
speed of rotation so dependent npon the travel of the 
piston is piston speed. Lnbrication is the main factor 
which determines piston speed, and the. higher the rate 
of piston travel the greater care must be taken to insnre 
proper oiling. Let us fully consider what is meant by 
piston speed. 

Assume that a motor has a piston travel or stroke of 
six inches, for the sake of illustration. It would take two 
strokes of the piston to cover one foot, or twelve inches, 
and as there are two strokes to a revolution it will be 
seen that this permits of a normal speed of 1,000 revolu- 
tions per minute for an engine with a six-inch stroke, if 
one does not exceed 1,000 feet per minute. If the stroke 
was only four inches, a normal speed of 1,500 revolutions 
per minute would be possible without exceeding the pre- 
scribed limit. The crank-shaft of a small engine, having 
three-inch stroke, could turn at a speed of 2,000 revolu- 
tions per minute without danger of exceeding the safe 
speed limit. It will be seen that the longer the stroke 
the slower the speed of the engine, if one desires to keep 
the piston speed within the bounds as recommended, but 
modern practice allows of greatly exceeding the speeds 
formerly thought best. 

ADVANTAGES OF OFF-SET CYLINDERS 

Another point upon which considerable difference of 
opinion exists relates to the method of placing the cylin- 
der upon the crank-case — i.e., whether its center line 
should be placed directly over the center of the crank- 
shaft, or to one side of center. The motor shown at 
Fig. 90 is an off-set type, in that the center line of the 



242 



Aviation Engines 



cylinder is a little to one side of the center of the crank- 
shaft. Diagrams are presented at Fig. 91 which show 
the advantages of off-set crank-shaft construction. The 



Rocker Arm 



.'Laminated leaf 
Spring 



Exhaust Valve- 



Exhaust Pipe-'' 



Applied Sheet--'' 
Metal Water Jacket 



Steel Cylinder- 



Intake Valve 




Fig. 90.— Cross Section of Austro-Daimler Engine, Showing Offset Cylinder 
Construction. Note Applied Water Jacket and Peculiar Valve Action. 

view at A is a section through a simple motor with the 
conventional cylinder placing, the center line of both 
crank-shaft and cylinder coinciding. The view at B shows 



Advantages of Offset Cylinders 



243 



the cylinder placed to one side of center so that its center 
line is distinct from that of the crank-shaft and at some 
distance from it. The amount of off-set allowed is a point 
of contention, the usual amount being from fifteen to 
twenty-five per cent, of the stroke. The advantages of 
the off-set are shown at Fig. 91, C. If the crank turns 





IS 

Note Decreased 
Side Thrust 
Because of Leaser 
Angle of 
Connecting Rod 




t" Resistance to 

Motion Center Line of 
Crank 



/] ' Center Line of 
Cylinder 



Fig. 91. — Diagrams Demonstrating Advantages of Offset Crank-Shaft 

Construction. 

in direction of the arrow there is a certain resistance to 
motion which is proportional to the amount of energy 
exerted by the engine and the resistance offered by the 
load. There are two thrusts acting against the cylinder 
wall to be considered, that due to explosion or expansion 
of the gas, and that which resists the motion of the piston. 
These thrusts may be represented by arrows, one which 
acts directly in a vertical direction on the piston top, the 



244 Aviation Engines 

other along a straight line through the center of the 
connecting rod. Between these two thrusts one can draw 
a line representing a resultant force which serves to bring 
the piston in forcible contact with one side of the cylinder 
wall, this being known as side thrust. As shown at C, 
the crank-shaft is at 90 degrees, or about one-half stroke, 
and the connecting rod is at 20 degrees angle. The 
shorter connecting rod would increase the diagonal re- 
sultant and side thrusts, while a longer one would reduce 
the angle of the connecting rod and the side thrust of 
the piston would be less. "With the off-set construction, 
as shown at D, it will be noticed that with the same con- 
necting-rod length as shown at C and with the crank- 
shaft at 90 degrees of the circle that the connecting-rod 
angle is 14 degrees and the side thrust is reduced pro- 
portionately. 

Another important advantage is that greater efficiency 
is obtained from the explosion with an off-set crank-shaft, 
because the crank is already inclined when the piston is 
at top center, and all the energy imparted to the piston 
by the burning mixture can be exerted directly into pro- 
ducing, a useful turning effort. When a cylinder is placed 
directly on a line with the crank-shaft, as shown at A, 
it will be evident that some of the force produced by the 
expansion of the gas will be exerted in a direct line and 
until the crank moves the crank throw and connecting 
rod are practically a solid member. The pressure which 
might be employed in obtaining useful turning effort is 
wasted by causing a direct pressure upon the lower half 
of the main bearing and the upper half of the crank-pin 
bushing. 

Very good and easily understood illustrations show- 
ing advantages of the off-set construction are shown at 
E and F. This is a bicycle crank-hanger. It is advanced 
that the effort of the rider is not as well applied when 
the crank is at position E as when it is at position F. 
Position E corresponds to the position of the parts when 
the cylinder is placed directly over the crank-shaft center. 



Valve Location Practice 245 

Position F may be compared to the condition which is 
present when the off-set cylinder construction is used. 

VALVE LOCATION OF VITAL IMPORT 

It has often been said that a chain is no stronger than 
its weakest link, and this is as true of the explosive motor 
as it is of any other piece of mechanism. Many motors 
which appeared to be excellently designed and which 
were well constructed did not prove satisfactory because 
some minor detail or part had not been properly consid- 
ered by the designer. A factor having material bearing 
upon the efficiency of the internal combustion motor is 
the location of the valves and the shape of the combus- 
tion chamber which is largely influenced by their placing. 
The fundamental consideration of valve design is that 
the gases be admitted and discharged from the cylinder 
as quickly as possible in order that the speed of gas flow 
will not be impeded and produce back pressure. This is 
imperative in obtaining satisfactory operation in any 
form of motor. If the inlet passages are constricted the 
cylinder will not fill with explosive mixture promptly, 
whereas if the exhaust gases are not fully expelled the 
parts of the inert products of combustion retained dilute 
the fresh charge, making it slow burning and causing lost 
power and overheating. When an engine employs water 
as a cooling medium this substance will absorb the sur- 
plus heat readily, and the effects of overheating are not 
noticed as quickly as when air-cooled cylinders are em- 
ployed. Valve sizes have a decided bearing upon the 
speed of motors and some valve locations permit the 
use of larger members than do other positions. 

While piston velocity is an important factor in de- 
terminations of power output, it must be considered from 
the aspect of the wear produced upon the various parts 
of the motor. It is evident that engines which run very 
fast, especially of high power, must be under a greater 
strain than those operating at lower speeds. The valve- 
operating mechanism is especially susceptible to the in- 



246 



Aviation Engines 



fluence of rapid movement, and the slower the engine the 
longer the parts will wear and the more reliable the 
valve action. 

As will be seen by reference to the accompanying illus- 
tration, Fig. 92, there are many ways in which valves may 
be placed in the cylinder. Each method outlined posses- 
ses some point of advantage, because all of the types 




Fig. 92. — Diagram Showing Forms of Cylinder Demanded "by Different Valve 
Placings. A — T Head Type, Valves on Opposite Sides. B — L Head 
Cylinder, Valves Side by Side. C — L Head Cylinder, One Valve in Head, 
Other in Pocket. D — Inlet Valve Over Exhaust Member, Both in Side 
Pocket. E — Valve-in-the-Head Type with Vertical Valves. F — Inclined 
Valves Placed to Open Directly into Combustion Chamber. 



Valve Location Practice 247 

illustrated are used by reputable automobile manufac- 
turers. The method outlined at Fig. 92, A, is widely 
used, and because of its shape the cylinder is known asf 
the "T" form. It is approved for automobile use fox 
several reasons, the most important being that large 
valves can be employed and a well-balanced and symmet- 
rical cylinder casting obtained. Two independent cam- 
shafts are needed, one operating the inlet valves, the 
other the exhaust members. The valve-operating mech- 
anism can be very simple in form, consisting of a plunger 
actuated by the cam which transmits the cam motion to 
the valve-stem, raising the valve as the cam follower 
rides on the point of the cam. Piping may be placed 
without crowding, and larger manifolds can be fitted than 
in some other constructions. This has special value, as 
it permits the use of an adequate discharge pipe on the 
exhaust side with its obvious advantages. This method 
of cylinder construction is never found on airplane en- 
gines because it does not permit of maximum power 
output. 

On the other hand, if considered from a viewpoint of 
actual heat efficiency, it is theoretically the worst form of 
combustion chamber. This disadvantage is probably com- 
pensated for by uniformity of expansion of the cylinder 
because of balanced design. The ignition spark-plug may 
be located directly over the inlet valve in the path of the 
incoming fresh gases, and both valves may be easily re- 
moved and inspected by unscrewing the valve caps with- 
out taking off the manifolds. 

The valve installation shown at C is somewhat un- 
usual, though it provides for the use of valves of large 
diameter. Easy charging is insured because of the large 
inlet valve directly in the top of the cylinder. Conditions 
may be reversed if necessary, and the gases discharged 
through this large valve. Both methods are used, though 
it would seem that the free exhaust provided by allowing 
the gases to escape directly from the combustion chamber 
through the overhead valve to the exhaust manifold 



248 Aviation Engines 

would make for more power. The method outlined at 
Fig. 92, F and at Fig. 90 is one that has been widely 
employed on large automobile racing motors where ex- 
treme power is required as well as in engines constructed 
for aviation service. The inclination of the valves per- 
mits the use of large valves, and these open directly into 
the combustion chamber. There are no pockets to retain 
heat or dead gas, and free intake and outlet of gas is 
obtained. This form is quite satisfactory from a theo- 
retical point of view because of the almost ideal combus- 
tion chamber form. Some difficulty is experienced, how- 
ever, in properly water-jacketing the valve chamber which 
experience has shown to be necessary if the engine is to 
have high power. 

The motor shown at Fig. 92, B and Fig. 88 employs 
cylinders of the "L" type. Both valves are placed in 
a common extension from the combustion chamber, and 
being located side by side both are actual from a com- 
mon cam-shaft. The inlet and exhaust pipes may be 
placed on the same side of the engine and a very com- 
pact assemblage is obtained, though this is optional if 
passages are cored in the cylinder pairs to lead the gases 
to opposite sides. The valves may be easily removed 
if desired, and the construction is fairly good from the 
viewpoint of both foundry man and machinist. The chief 
disadvantage is the limited area of the valves and the 
loss of heat efficiency due to the pocket. This form of 
combustion chamber, however, is more efficient than the 
"T" head construction, though with the latter the use of 
larger valves probably compensates for the greater heat 
loss. It has been stated as an advantage of this con- 
struction that both manifolds can be placed at the same 
side of the engine and a compact assembly secured. On 
the other hand, the disadvantage may be cited that in 
order to put both pipes on the same side they must be 
of smaller size than can be used when the valves are 
oppositely placed. The "L" form cylinder is sometimes 
made more efficient if but one valve is placed in the pocket 



Valve Location Practice 



249 



while the other is placed over it. This construction is 
well shown at Fig. 92, D and is found on Anzani motors. 
The method of valve application shown at Fig. 87 is 
an ingenious method of overcoming some of the disad- 
vantages inherent with valve-in-the-head motors. In the 
first place it is possible to water-jacket the valves thor- 



Rpcker Arm Shaft-—- 

Oil Cap " 

Adjusting Ball End ->g| 

Lock Nut 



Valve Lifter Guide->~*. 
Valve Lifter- 



■Valve Rocker Arm 

■Valve Stem 

— Valve Spring 

Valve Cage Nut 

—-Valve Cage 

Packing Ring 

'"-Valve Cage 

--Valve 




Fig. 93. — Sectional View of Engine Cylinder Showing Valve and Cage 

Installation. 

oughly, which is difficult to accomplish when they are 
mounted in cages. The water circulates directly around 
the walls of the valve chambers, which is superior to a 
construction where separate cages are used, as there are 
two thicknesses of metal with the latter, that of the valve- 
cage proper and the wall of the cylinder. The cooling 
medium is in contact only with the outer wall, and as 
there is always a loss of heat conductivity at a joint it 



250 



Aviation Engines 



is practically impossible to keep the exhaust valves and 
their seats at a uniform temperature. The valves may 
be of larger size without the use of pockets when seating 
directly in the head. In fact, they could be equal in 




Tig. 94. — Diagrams Showing How Gas Enters Cylinder Through Overhead 
Valves and Other Types. A — Tee Head Cylinder. B — L Head Cylinder. 
C — Overhead Valve. 

diameter to almost half the bore of the cylinder, which 
provides an ideal condition of charge placement and ex- 
haust. When valve grinding is necessary the entire head 
is easily removed by taking off six nuts and loosen- 
ing inlet manifold connections, which operation would 
be necessary even if cages were employed, as in the 
engine shown at Fig. 93. 



Valve Location Practice 



251 



At Fig. 94, A and B, a section through a typical "L"- 
shaped cylinder is depicted. It will be evident that where 
a pocket constrnction is employed, in addition to its fac- 
ulty for absorbing heat, the passage of gas would be 
impeded. For example, the inlet gas rushing in through 
the open valve would impinge sharply upon the valve-cap 
or combustion head directly over the valve and then must 
turn at a sharp angle to enter the combustion chamber 






Corns 






Stem 




fa/ve 



Fig. 95. — Conventional Methods of Operating Internal Combustion Motor 

Valves. 



252 



Aviation Engines 



and then at another sharp angle to fill the cylinders. The 
same conditions apply to the exhanst gases, though they 
are reversed. When the valve-in-the-head type of cylin- 
der is employed, as at C, the only resistance offered the 
gas is in the manifold. As far as the passage of the 
gases in and out of the cylinder is concerned, ideal condi- 
tions obtain. It is claimed that valve-in-the-head motors 
are more flexible and responsive than other forms, bnt the 
construction has the disadvantage in that the valves must 
be opened through a rather complicated system of push 




Fig. 96. — Examples of Direct Valve Actuation by Overhead Cam-Shaft. 
A — Mercedes. B — Hall-Scott. C — Wisconsin. 

rods and rocker arms instead of the simpler and direct 
plunger which can be used with either the "T" or "L" 
head cylinders. This is clearly outlined in the illustra- 
tions at Fig. 95, where A shows the valve in the head- 
operating mechanism necessary if the cam-shaft is car- 
ried at the cylinder base, while B shows the most direct 
push-rod action obtained with "T" or "L" head cylinder 
placing. 

The objection can be easily met by carrying the cam- 
shaft above the cylinders and driving it by means of 
gearing. The types of engine cylinders using this con- 
struction are shown at Fig. 96, and it will be evident that 
a positive and direct valve action is possible by following 
the construction originated by the Mercedes (German) 



Valve Location Practice 253 



Fig. 97. 

CENSORED 



254 Aviation Engines 



Fig. 98. 

CENSORED 



aviation engine designers and outlined at A. The other 
forms at B and C are very clearly adaptations of this 
design. The Hall-Scott engine at Fig. 97 is depicted in 
part section and no trouble will be experienced in under- 
standing the bevel pinion and gear drive from the crank- 



Concentric Valve Design 



255 



shaft to the overhead cam-shaft through a vertical coun- 
ter-shaft. A very direct valve action is used in the 
Duesenberg engines, one of which is shown in part section 
at Fig. 98. The valves are parallel with the piston top 
and are actuated by rocker arms, one end of which bears 
against the valve stem, and the other rides the cam-shaft. 



-Main Rocker Arm 




Double 
Auxiliary Rocker ' B Profile 

Arm for Inlet Cam 

Valve 



Section at A-B 



Inlet 
Valve 
Open 



Fig. 99. — Sectional Views Showing Arrangement of Novel Concentric Valve 
Arrangement Devised by Panhard for Aerial Engines. 

The form shown at Fig. 99 shows an ingenious appli- 
cation of the valve-in-the-head idea which permits one 
to obtain large valves. It has been used on some of the 
Panhard aviation engines and on the American Aero- 
marine power plants. The inlet passage is controlled 
by the sliding sleeve which is hollow and slotted so as 
to permit the inlet gases to enter the cylinder through 
the regular type poppet valve which seats in the exhaust 
sleeve. "When the exhaust valve is operated by the tap- 
pet rod and rocker arm the intake valve is also carried 



256 Aviation Engines 

down with it. The intake gas passage is closed, however, 
and the burned gases are discharged through the large 
annular passage surrounding the sleeve. When the inlet 
valve leaves its seat in the sleeve the passage of cool 
gas around the sleeve keeps the temperature of both 
valves to a low point and the danger of warping is mini- 
mized. A dome-shaped combustion chamber may be used, 
which is an. ideal form in conserving heat efficiency, and 
as large values may be installed the flow of both fresh 
and exhaust gases may be obtained with minimum resist- 
ance. The intake valve is opened by a small auxiliary 
rocker arm which is lifted when, the cam follower rides 
into the depression in the cam by the action of the strong 
spring around the push rod. When the cam follower rides 
on the high point the exhaust sleeve is depressed from 
its seat against the cylinder. By using a cam having both 
positive and negative profiles, a single rod suffices for 
both valves because of its push and pull action. 

VALVE DESIGN AND CONSTRUCTION 

Valve dimensions are an important detail to be con- 
sidered and can be determined by several conditions, 
among which may be cited method of installation, oper- 
ating mechanism, material employed, engine speed de- 
sired, manner of cylinder cooling and degree of lift 
desired. A review of various methods of valve location 
has shown that when the valves are placed directly in 
the head we can obtain the ideal cylinder form, though 
larger valves may be used if housed in a separate pocket, 
as afforded by the "T" head construction. The method 
of operation has much to do with the size of the valves. 
For example, if an automatic inlet valve is employed it 
is good practice to limit the lift and obtain the required, 
area of port opening by augmenting the diameter. Be- 
cause of this a valve of the automatic type is usually 
made twenty per cent, larger than one mechanically oper- 
ated. When both are actuated by cam mechanism, as is 
now common practice, they are usually made the same 



Valve Design and Construction 257 

size and are interchangeable, which greatly simplifies 
mannf actnre. The relation of valve diameter to cylin- 
der bore is one that has been discussed for some time 
by engineers. The writer's experience would indicate that 
they shonld be at least half the bore, if possible. "While 
the mushroom type or poppet valve has become standard 
and is the most widely used form at the present time, 
there is some difference of opinion among designers as 
to the materials employed and the angle of the seat. Most 
valves have a bevel seat, though some have a flat seating. 
The flat seat valve has the distinctive advantage of pro- 
viding a clear opening with lesser lift, this conducing to 
free gas flow. It also has value because it is silent in 
operation, but the disadvantage is present that best mate- 
rial and workmanship must be used in their construction 
to obtain satisfactory results. As it can be made very 
light it is particularly well adapted for use as an auto- 
matic inlet valve. Among other disadvantages cited is 
the claim that it is more susceptible to derangement, owing 
to the particles of foreign matter getting under the seat. 
With a "bevel seat it is argued that the foreign matter 
would be more easily dislodged by the gas flow, and that 
the valve would close tighter because it is drawn posi- 
tively against the bevel seat. 

Several methods of valve construction are the vogue, 
the most popular form being the one-piece type; those 
which are composed of a head of one material and stem 
of another are seldom used in airplane engines because 
they are not reliable. In the built-up construction the 
head is usually of high nickel steel or cast iron, which 
metals possess good heat-resisting qualities. Heads made 
of these materials are not likely to warp, scale, or pit, 
as is sometimes the case when ordinary grades of ma- 
chinery steel are used. The cast-iron head construction 
is not popular because it is often difficult to keep the head 
tight on the stem. There is a slight difference in ex- 
pansion ratio between the head and the stem, and as the 
stem is either screwed or riveted to the cast-iron head 



258 



Aviation Engines 



the constant hammering of the valve against its seat may 
loosen the joint. As soon as the head is loose on the stem 
the action of the valve becomes erratic. The best practice 
is to machine the valves from tungsten steel forgings. 
This material has splendid heat-resisting qualities and 
will not pit or become scored easily. Even the electri- 
cally welded head to stem types which are used in auto- 




Fig. 



100. — Showing Clearance Allowed Between Valve 
and Valve Stem Guide to Secure Free Action. 



Stem 



mobile engines are not looked upon with favor in the 
aviation engine. Valve stem guides and valve stems must 
be machined very accurately to insure correct action. The 
usual practice in automobile engines is shown at Fig. 100. 



VALVE OPERATION 

The methods of valve operation commonly used vary 
according to the type of cylinder construction employed. 
In all cases the valves are lifted from their seats by cam- 
actuated mechanism. Various forms of valve-lifting cams 
are shown at Fig. 101. As will be seen, a cam consists 



Valve-Lifting Cams 



259 



of a circle to which a raised, approximately triangular 
member has been added at one point. When the cam 
follower rides on the circle, as shown at Fig. 102, there 
is no difference in height between the cam center and its 
periphery and there is no movement of the plunger. As 
soon as the raised portion of the cam strikes the plunger 
it will lift it, and this reciprocating movement is trans- 
mitted to the valve stem by suitable mechanical connec- 
tions. 

The cam forms outlined at Fig. 101 are those com- 
monly used. That at A is used on engines where it is 




Fig. 101. — Forms of Valve-Lifting Cams Generally Employed. A — Cam 
Profile for Long Dwell and Quick Lift. B — Typical Inlet Cam Used 
with Mushroom Type Follower. C — Average Form of Cam. D — 
Designed to Give Quick Lift and Gradual Closing. 



desired to obtain a quick lift and to keep the valve fully 
opened as long as possible. It is a noisy form, however, 
and is not very widely employed. That at B is utilized 
more often as an inlet cam while the profile shown at C 
is generally depended on to operate exhaust valves. The 
cam shown at D is a composite form which has some 
of the features of the other three types. It will give the 
quick opening of form A, the gradual closing of form B, 
and the time of maximum valve opening provided by cam 
profile C. 

The various types of valve plungers used are shown 
at Fig. 102. That shown at A is the simplest form, con- 
sisting of a simple cylindrical member having a rounded 
end which follows the cam profile. These are sometimes 



260 



Aviation Engines 



made of square stock or kept from rotating by means of 
a key or pin. A line contact is possible when the plunger 
is kept from turning, whereas but a single point bearing 
is obtained when the plunger is cylindrical and free to 
revolve. The plunger shown at A will follow only cam 
profiles which have gradual lifts. The plunger shown at 
B is left free to revolve in the guide bushing and is pro- 




Fig. 102. — Showing Principal Types of Cam Followers which Have Received 

General Application. 

vided with a flat mushroom head which serves as a cam 
follower. The type shown at C carries a roller at its 
lower end and may follow very irregular cam profiles if 
abrupt lifts are desired. While forms A and B are the 
simplest, that outlined at C in its various forms is more 
widely used. Compound plungers are used on the Curtiss 
0X2 motors, one inside the other. The small or inner one 
works on a cam of conventional design, the outer plunger 
follows a profile having a flat spot to permit. of a pull 
rod action instead of a push rod action. All the methods 
in which levers are used to operate valves are more or 
less noisy because clearance must be left between the valve 
stem and the stop of the plunger. The space must be 
taken up before the valve will leave its seat, and when 



Valve-Stem Clearances 



261 



the engine is operated at high speeds the forcible contact 
between the plunger and valve stem produces a rattling 
sound until the valves become heated and expand and the 
stems lengthen out. Clearance must be left between the 
valve stems and actuating means. This clearance is clearly 
shown in Fig. 103 and should be .020" (twenty thou- 
sandths) when engine is cold. The amount of clearance 
allowed depends entirely upon the design of the engine 



.„_i, c ,Cam Follower 

.Lock Screw 

^-Adjusting / ,* Rocker 

\ ,/ Screw s'Fulcrum-;^-/ Levers 



Lock 
• Screw 




Valve-"' 
Stem 



Clearance 
.020 



Fig. 103. — Diagram Showing Proper Clearance to Allow Between Adjust- 
ing Screw and Valve Stems in Hall-Scott Aviation Engines. 

and length of valve stem. On the Curtiss 0X2 engines 
the clearance is but .010" (ten thousandths) because the 
valve stems are shorter. Too little clearance will result 
in loss of power or misfiring when engine is hot. Too 
much clearance will not allow the valve to open its full 
amount and will disturb the timing:. 



METHODS OF DRIVING CAM-SHAFT 

I 

Two systems of cam-shaft operation are used. The 
most common of these is by means of gearing of some 
form. If the cam-shaft is at right angles to the crank- 
shaft it may be driven by worm, spiral, or bevel gearing. 



262 



Aviation Engines 



If the cam-shaft is parallel to the crank-shaft, simple spur 
gear or chain connection may be used to turn it. A typi- 
cal cam-shaft for an eight-cylinder V engine is shown at 
Fig. 104. It will be seen that the sixteen cams are forged 
integrally with the shaft and that it is spur-gear driven. 
The cam-shaft drive of the Hall-Scott motor is shown at 
Fig. 97. 

While gearing is more commonly used, considerable 
attention has been directed of late to silent chains for 
cam-shaft operation. The ordinary forms of block or 
roller chain have not proven successful in this applica- 



r- 


f^tr Driving Gear 
K5 /.Cams 








Y. 


Rear Bearing \ 




:..'«ar 

I 


W \ Cc ~ 


rr 


■Shi 


ik;- 




■Center Bearing . 




-- 9K 


jay ^Cam-Shaft Bearing 












, 


L 














i L„J 



Tig. 104. — Cam-Shaft of Thomas Airplane Motor Has Cams Forged Integ- 
ral. Note Split Cam-Shaft Bearings and Method of Gear Betention. 



tion, but the silent chain, which is in reality a link belt 
operating over toothed pulleys, has demonstrated its 
worth. The tendency to its use is more noted on foreign 
motors than those of American design. It first came to 
public notice when employed on the Daimler-Knight en- 
gine for driving the small auxiliary crank-shafts which 
reciprocated the sleeve valves. The advantages cited for 
the application of chains are, first, silent operation, which 
obtains even after the chains have worn considerably; 
second, in designing it is not necessary to figure on main- 
taining certain absolute center distances between the 
crank-shaft and cam-shaft sprockets, as would be the case 
if conventional forms of gearing were used. On some 
forms of motor employing gears, three and even four 



Valve Springs 263 

members are needed to turn the cam- shaft. "With a chain 
drive but two sprockets are necessary, the chain forming 
a flexible connection which permits the driving and driven 
members to be placed at any distance apart that the 
exigencies of the design demand. When chains are used 
it is advised that some means for compensating chain 
slack be provided, or the valve timing will lag when 
chains are worn. Many combination drives may be 
worked out with chains that would not be possible with 
other forms of gearing. Direct gear drive is favored at 
the present time Jby airplane engine designers because they 
are the most certain and positive means, even when a 
number of gears must be used as intermediate drive 
members. With overhead cam-shafts, bevel gears work 
out very well in practice, as in the Hall-Scott motors and 
others of that type. 

VALVE SPRINGS 

Another consideration of importance is the use of 
proper valve- springs, and particular care should be taken 
with those of automatic valves. The spring must be weak 
enough to allow the valve to open when the suction is 
light, and must be of sufficient strength to close it in 
time at high speeds. It should be made as large as pos- 
sible in diameter and with a large number of convolutions, 
in order that fatigue of the metal be obviated, and it is 
imperative that all springs be of the same strength when 
used on a multiple-cylinder engine. Practically all valves 
used to control the gas flow in airplane engines are me- 
chanically operated. On the exhaust valve the spring 
must be strong enough so that the valve will not be sucked 
in on the inlet stroke. It should be borne in mind that 
if the spring is too strong a strain will be imposed on 
the valve-operating mechanism, and a hammering action 
produced which may cause deformation of the valve-seat. 
Only pressure enough to insure that the operating mech- 
anism will follow the cam is required. It is common 
practice to make the inlet and exhaust valve springs of 



264 



Aviation Engines 



the same tension when the valves are of the same size 
and both mechanically operated. This is done merely to 
simplify manufacture and not because it is necessary for 



Spark Plug 



^ Relief Cock 

JR Cylinder Head 



Cranks 
Operating 
Sleeves 




Outer Sleeue 



\ - — inner Sleeue 

1 



Fig. 105. — Section Through Cylinder of Knight Motor, Showing Important 
Parts of Valve Motion. 

the inlet valve-spring to be as strong as the other. Valve 
springs of the helical coil type are generally used, though 
torsion or "scissors" springs and laminated or single- 
leaf springs are also utilized in special applications. Two 



Valve Springs 



265 



springs are used on each valve in some valve-in-the-head 
types ; a spring of small pitch diameter inside the regular 
valve-spring and concentric with it. Its function is to * 



Intake-- 




Tiring Stroke -All Ports Closed 



Exhaust Stroke -Exhaust Ports Open 



Fig. 106. — Diagrams Showing Knight Sleeve Valve Action. 



keep the valve from falling into the cylinder in event of 
breakage of the main spring in some cases, and to provide 
a stronger return action in others. 



266 Aviation Engines 

KNIGHT SLIDE VALVE MOTOR 

The sectional view through the cylinder at Fig. 105 
shows the Knight sliding sleeves and their actuating 
means very clearly. The diagrams at Fig. 106 show 
graphically the sleeve movements and their relation to 
the crank-shaft and piston travel. The action may be 
summed up as follows: The inlet port begins to open 
when the lower edge of the opening of the outside sleeve 
which is moving down passes the top of the slot in the 
inner member also moving downwardly. The inlet port 
is closed when the lower edge of the slot in the inner 
sleeve which is moving up passes the top edge of the port 
in the outer sleeve which is also moving toward the top 
of the cylinder. The inlet opening extends over two hun- 
dred degrees of crank motion. The exhaust port is un- 
covered slightly when the lower edge of the port in the 
inner sleeve which is moving down passes the lower edge 
of the portion of the cylinder head which protrudes in 
the cylinder. When the top of the port in the outer sleeve 
traveling toward the bottom of the cylinder passes the 
lower edge of the slot in the cylinder wall the exhaust 
passage is closed. The exhaust opening extends over a 
period corresponding to about two hundred and forty 
degrees of crank motion. The Knight motor has not been 
applied to aircraft to the writer's knowledge, but an 
eight-cylinder Vee design that might be useful in that 
connection if lightened is shown at Fig. 107. The main 
object is to show that the Knight valve action is the only 
other besides the mushroom or poppet valve that has been 
applied successfully to high speed gasoline engines. 

VALVE TIMING 

It is in valve timing that the greatest difference of 
opinion prevails among engineers, and it is rare that one 
will see the same formula in different motors. It is true 
that the same timing could not be used with motors of 



Valve-Timing Practice 



267 



different construction, as there are many factors which 
determine the amount of lead to be given to the valves. 
The most important of these is the relative size of the 
valve to the cylinder bore, the speed of rotation it is 



; P riming Cups -^ 



Cylinder Oil Lead, 
Wiring Header, 
Junk Ring, \ 



flnlet Manifold 

•Ignition 
/ Distributor 



..-- Wiring Header 

\-~Hot Air Conn 
toCarburetor 




Piston--'' 

Ex. Pipe. / 

Cylinder- '" 

Outer Sleeve^ -"""" .-' 

Inner Sleeve-'''' S' 
Conn. Rod-~" 
Oil. By- pass Body Valve' 
Math Bearing Oil Lead-' 



\-Long EccShaft Rod 
"Short EccShaft Rod 

' Eccentric Shafts 



Crank-Shaft with 
Counter- weight 



J)rain Plug--'" 



''Oil Strainer 



>.6.h»*st»o»<' 



Fig. 107. — Cross Sectional View of Knight Type Eight Cylinder V Engine. 



desired to obtain, the fuel efficiency, the location of the 
valves, and other factors too numerous to mention. 

Most of the readers should be familiar with the cycle 
of operation of the internal combustion motor of the 
four-stroke type, and it seems unnecessary to go into 
detail except to present a review. The first stroke of the 
piston is one in which a charge of gas is taken into the 



268 Aviation Engines 

motor; the second stroke, which is in reverse direction 
to the first, is a compression stroke, at the end of which 
the spark takes place, exploding the charge and driving 
the piston down on the third or expansion stroke, which 
is in the same direction as the intake stroke, and finally, 
after the piston has nearly reached the end of this stroke, 
another valve opens to allow the bnrned gases to escape,, 
and remains open nntil the piston has reached the end 
of the fonrth stroke and is in a position to begin the 
series over again. The ends of the strokes are reached 
when the piston comes to a stop at either top or bottom 
of the cylinder and reverses its motion. That point is 
known as a center, and there are two for each cylinder, 
top and bottom centers, respectively. 

All circles may be divided into 360 parts, each of 
which is known as a degree, and, in tnrn, each of these 
degrees may be again divided into minntes and seconds, 
though we need not concern onrselves with anything less 
than the degree. Each stroke of the piston represents 
180 degrees travel of the crank, because two strokes rep- 
resent one complete revolution of three hundred and sixty 
degrees. The top and bottom centers are therefore sep- 
arated by 180 degrees. Theoretically each phase of a 
four-cycle engine begins and ends at a center, though in 
actual practice the inertia or movement of the gases 
makes it necessary to allow a lead or lag to the valve, as 
the case may be. If a valve opens before a center, the 
distance is called "lead"; if it closes after a center, this 
distance is known as "lag." The profile of the cams 
ordinarily used to open or close the valves represents a 
considerable time in relation to the 180 degrees of the 
crank-shaft travel, and the area of the passages through 
which the gases are admitted or exhausted is quite small 
owing to the necessity of having to open or close the 
valves at stated times; therefore, to open an adequately 
large passage for the gases it is necessary to open the 
valves earlier and close them later than at centers. 
That advancing the opening of the exhaust valve was 



Valve-Timing Practice 269 

of value was discovered on the early motors and is ex- 
plained by the necessity of releasing a large amount of 
gas, the volume of which has been greatly raised by the 
heat of combustion. When the inlet valves were mechan- 
ically operated it was found that allowing them to lag 
at closing enabled the inspiration of a greater volume of 
gas. Disregarding the inertia or flow of the gases, open- 
ing the exhaust at center would enable one to obtain full 
value of the expanding gases the entire length of the 
piston stroke, and it would not be necessary to keep the 
valve open after the top center, as the reverse stroke 
would produce a suction effect which might draw some 
of the inert charge back into the cylinder. On the other 
hand, giving full consideration to the inertia of the gas, 
opening the valve before center is reached will provide 
for quick expulsion of the gases, which have sufficient 
velocity at the end of the stroke, so that if the valve is 
allowed to remain open a little longer, the amount of lag 
varying with the opinions of the designer, the cylinder 
is cleared in a more thorough manner. 

BLOWING BACK 

When the factor of retarded opening is considered 
without reckoning the inertia of the gases, it would 
appear that if the valve were allowed to remain open 
after center had passed, say, on the closing of the inlet, 
the piston, having reversed its motion, would have the 
effect of expelling part of the fresh charge through the 
still open valve as it passed inward at its compression 
stroke. This effect is called blowing back, and is often 
noted with motors where the valve settings are not ab- 
solutely correct, or where the valve-springs or seats are 
defective and prevent proper closing. 

This factor is not of as much import as might appear, 
as on closer consideration it will be seen that the move- 
ment of the piston as the crank reaches either end of the 
stroke is less per degree of angular ■ movement than it 
is when the angle of the connecting rod is greater. Then, 



270 Aviation Engines 

again, a certain length of time is required for the reversal 
of motion of the piston, during which time the crank is 
in motion but the piston practically at a standstill. If the 
valves are allowed to remain open during this period, 
the passage of the gas in or out of the cylinder will be 
by its own momentum. 

LEAD GIVEN EXHAUST VALVE 

The faster a motor turns, all other things being equal, 
the greater the amount of lead or advance it is necessary 
to give the opening of the exhaust valve. It is self-evi- 
dent truth that if the speed of a motor is doubled it 
travels twice as many degrees in the time necessary to 
lower the pressure. As most designers are cognizant of 
this fact, the valves are proportioned accordingly. It is 
well to consider in this respect that the cam profile has 
much to do with the manner in which the valve is opened ; 
that is, the lift may be abrupt and the gas allowed to 
escape in a body, or the opening may be gradual, the 
gas issuing from the cylinder in thin streams. An analogy 
may be made with the opening of any bottle which con- 
tains liquid highly carbonated! If the cork is removed 
suddenly the gas escapes with a loud pop, but, on the 
other hand, if the bottle is uncorked gradually, the gas 
escapes from the receptacle in thin streams around the 
cork, and passage of the gases to the air is accomplished 
without noise. While the second plan is not harsh, it 
is slower than the former, as must be evident. 

EXHAUST CLOSING, INLET OPENING 

A point which has been much discussed by engineers 
is the proper relation of the closing of the exhaust valve 
and the opening of the inlet. Theoretically they should 
succeed each other, the exhaust closing at upper dead 
center and the inlet opening immediately afterward. The 
reason why a certain amount of lag is given the exhaust 
closing in practice is that the piston cannot drive the 



Valve-Timing Practice 271 

gases out of the cylinder unless they are compressed to 
a degree in excess of that existing in the manifold or 
passages, and while toward the end of the stroke this 
pressure may be feeble, it is nevertheless indispensable. 
At the end of the piston's stroke, as marked by the upper 
dead center, this compression still exists, no matter how 
little it may be, so that if the exhaust valve is closed and 
the inlet opened immediately afterward, the pressure 
which exists in the cylinder may retard the entrance of 
the fresh gas and a certain portion of the inert gas may 
penetrate into the manifold. As the piston immediately 
begins to aspirate, this may not be serious, but as these 
gases are drawn back into the cylinder the fresh charge 
will be diluted and weakened in value. If the spark-plug 
is in a pocket, the points may be surrounded by this weak 
gas, and the explosion will not be nearly as energetic as 
when the ignition spark takes place in pure mixture. 

It is a well-known fact that the exhaust valve should 
close after dead center and that a certain amount of lag 
should be given to opening, of the inlet. The lag given 
the closing of the exhaust valve should not be as great 
as that given the closing of the inlet valve. Assuming 
that the excess pressure of the exhaust will equal the 
depression during aspiration, the time necessary to com- 
plete the emptying of the cylinder will be proportional 
to the volume of the gas within it. At the end of the 
suction stroke the volume of gas contained in the cylinder 
is equal to the cylindrical volume plus the space of the 
combustion chamber. At the end of the exhaust stroke 
the volume is but that of the dead space, and from one- 
third to one-fifth its volume before compression. While 
it is natural to assume that this excess of burned gas 
will escape faster than the fresh gas will enter the cylin- 
der, it will be seen that if the inlet valve were allowed 
to lag twenty degrees, the exhaust valve lag need not be 
more than five degrees, providing that the capacity of 
the combustion chamber was such that the gases occupied 
one-quarter of their former volume. 



272 Aviation Engines 

It is evident that no absolute rule can be given, as 
back pressure will vary with the design of the valve 
passages, the manifolds, and the construction of the 
muffler. The more direct the opening, the sooner the 
valve can be closed and the better the cylinder cleared. 
Ten degrees represent an appreciable angle of the crank, 
and the time required for the crank to cover this angular 
motion is not inconsiderable and an important quantity of 
the exhaust may escape, but the piston is very close to 
the dead center after the distance has been covered. 

Before the inlet valve opens there should be a certain 
depression in the cylinder, and considerable lag may be 
allowed before the depression is appreciable. So far as 
the volume of fresh gas introduced during the admission 
stroke is concerned, this is determined by the displace- 
ment of the piston between the point where the inlet valve 
opens and the point of closing, assuming that sufficient 
gas has been inspired so that an equilibrium of pressure 
has been established between the interior of the cylinder 
and the outer air. The point of inlet opening varies with 
different motors. It would appear that a fair amount of 
lag would be fifteen degrees past top center for the inlet 
opening, as a certain depression will exist in the cylinder, 
assuming that the exhaust valve has closed five or ten 
degrees after center, and at the same time the piston has 
not gone down far enough on its stroke to materially 
decrease the amount of gas which will be taken into the 
cylinder. 

CLOSING THE INLET VALVE 

As in the case with the other points of opening and 
closing, there is a wide diversity of practice as relates 
to closing the inlet valve. Some of the designers close 
this exactly at bottom center, but this practice cannot 
be commended, as there is a considerable portion of time, 
at least ten or fifteen degrees angular motion of the crank, 
before the piston will commence to travel to any extent 
on its compression stroke. The gases rushing into the 



Valve-Timing Practice 273 

cylinder have considerable velocity, and unless an equi- 
librium is obtained between the pressure inside and that 
of the atmosphere outside, they will continue to rush into 
the cylinder even after the niston ceases to exert any 
suction effect. 

For this reason, if the valve is closed exactly on cen- 
ter, a full charge may not be inspired into the cylinder, 
though if the time of closing is delayed, this momentum 
or inertia of the gas will be enough to insure that a 
maximum charge is taken into the cylinder. The writer 
considers that nothing will be gained if the valve is al- 
lowed to remain open longer than twenty degrees, and an 
analysis of practice in this respect would seem to confirm 
this opinion. From that point in the crank movement 
the piston travel increases and the compressive effect is 
appreciable, and it would appear that a considerable pro- 
portion of the charge might be exhausted into the mani- 
fold and carburetor if the valve were allowed to remain 
open beyond a point corresponding to twenty degrees 
angular movement of the crank. 

TIME OF IGNITION 

In this country engineers unite in providing a vari- 
able time of ignition, though abroad some difference of 
opinion is noted on this point. The practice of advanc- 
ing the time of ignition, when affected electrically, was 
severely condemned by early makers, these maintaining 
that it was necessary because of insufficient heat and 
volume of the spark, and it was thought that advancing 
ignition was injurious. The engineers of to-day appre- 
ciate the fact that the heat of the electric spark, espe- 
cially when from a mechanical generator of electrical 
energy, is the only means by which we can obtain prac- 
tically instantaneous explosion, as required by the opera- 
tion of motors at high speeds, and for the combustion 
of large volumes of gas. 

It is apparent that a motor with a fixed point of 



274 



Aviation Engines 



ignition is not as desirable, in every way, as one in which 
the ignition can be advanced to best meet different re- 
quirements, and the writer does not readily perceive any 



*S Position of No. I Cylinder Cams 

when No. I Piston is on top dead center 




Part K 
Diagram of Gears in Hall-Scott 
Type A-5 Aviation Motor 

.Exhaust Closed 

Magneto \ ^ 
fully \^ 
Advanced'/ 



Part B 









\LJ j — ~L ; . * V ^ J 












lojsj 



Section thru Cam Shaft 
Housing Showing position of 



Cams. when 



Exhaust Va Ive is Closed 



intake Closed-' 



Exhaust 
Open 



Note on Chart that Crank-Shaft 
is 10° past top center when 
Exhaust Valve is closed 



cq <o 



fig. 108. — Diagrams Explaining Valve and Ignition Timing of Hall-Scott 

Aviation Engine. 



advantage outside of simplicity of control in establishing 
a fixed point of ignition. In fact, there seems to be some 
difference of opinion among those designers who favor 



Ignition Timing 



275 



fixed ignition, and in one case this is located forty- three 
degrees ahead of center, and in another motor the point 
is fixed at twenty degrees, so that it may be said that 
this will vary as much as one hundred per cent, in various 
forms. This point will vary with different methods of 



Dead Center 


1* 


6 


___ -> 


* 1 


^-"C^j^i 


sra^-v. 




\ /^^^^. -V 




Q *1 X. ° 


/ <§ 






•*- Q) \ v 


V / * 


,* NT-* \ \ 


/ / 
/ / 


^ ^^ \ \ 


1 1 




v ^ /^S,. 


^^^ Jp 




^**^ / 


'-- !20 o —"-'" 







Fig. 109. — Timing Diagram of Typical Six-Cylinder Engine. 



ignition, as well as the location of the spark-plug or 
igniter. For the sake of simplicity, most airplane en- 
gines use set spark; if an advancing and retarding mech- 
anism is fitted, it is only to facilitate starting, as the 
spark is kept advanced while in flight, and control is by 
throttle alone. 

It is obvious by consideration of the foregoing that 
there can be no arbitrary rules established for timing, 



276 



Aviation Engines 



because of the many conditions which determine the best 
times for opening and closing the valves. It is customary 
to try various settings when a new motor is designed 
until the most satisfactory points are determined, and 
th6 setting which will be very suitable for one motor is 
not always right for one of different design. The timing 




Fig. 110. — Timing Diagram of Typical Eight-Cylinder V Engine. 



diagram shown at Fig. 108 applies to the Hall-Scott 
engine, and may be considered typical. It should be 
easily followed in view of the very complete explanation 
given in preceding pages. Another six-cylinder engine 
diagram is shown at Fig. 109, and an eight-cylinder tim- 
ing diagram is shown at Fig. 110. In timing automobile 
engines no trouble is experienced, because timing marks 



How an Engine is Timed 277 

are always indicated on the engine fly-wheel register with 
an indicating trammel on the crank-case. To time an 
airplane engine accurately, as is necessary to test for a 
suspected cam-shaft defect, a timing disc of aluminum is 
attached to the crank-shaft which has the timing marks 
indicated thereon. If the disc is made 10 or 12 inches 
in diameter, it may be divided into degrees without 
difficulty. 

HOW AN" ENGINE IS TIMED 

In timing a motor from the marks on the timing disc 
rim it is necessary to regulate the valves of but one 
cylinder at a time. Assuming that the disc is revolving 
in the direction of engine rotation, and that the firing 
order of the cylinders is 1-3-4-2, the operation of timing 
would be carried on as follows: The crank-shaft would 
be revolved until the line marked "Exhaust opens 1 and 
4" registered with the trammel on the motor bed. At this 
point the exhaust-valve of either cylinder No. 1 or No. 4 
should begin to open. This can be easily determined by 
noting which of these cylinders holds the compressed 
charge ready for ignition. Assuming that the spark has 
occurred in cylinder No. 1, then when the fly-wheel is 
turned from the position to that in which the line marked 
"Exhaust opens 1 and 4" coincides with the trammel 
point, the valve-plunger under the exhaust-valve of cylin- 
der No. 1 should be adjusted in such a way that there is 
no clearance between it and the valve stem. Further 
movement of the wheel in the same direction should pro- 
duce a lift of the exhaust valve. The disc is turned about 
two hundred and twenty-five degrees, or a little less than 
three-quarters of a revolution; then the line marked 
"Exhaust closes 1 and 4" will register with the trammel 
point. At this period the valve-plunger and the valve- 
stem should separate and a certain amount of clearance 
obtain between them. The next cylinder to time would 
be No. 3. The crank-shaft is rotated until mark "Exhaust 
opens 2 and 3" comes in line with the trammel. At this 



278 Aviation Engines 

point the exhaust valve of cylinder No. 3 should be just 
about opening. The closing is determined by rotating the 
shaft until the line "Exhaust closes 2 and 3" comes 
under the trammel. 

This operation is carried on with all the cylinders, 
it being well to remember that but one cylinder is work- 
ing at a time and that a half -revolution of the fly-wheel 
corresponds to a full working stroke of all the cylinders, 
and that while one is exhausting the others are respec- 
tively taking in a new charge, compressing and exploding. 
For instance, if cylinder No. 1 has just completed its 
power-stroke, the piston in cylinder No. 3 has reached 
the point where the gas may be ignited to advantage. 
The piston of cylinder No. 4, which is next to fire, is at 
the bottom of its stroke and will have inspired a charge, 
while cylinder No. 2, which is the last to fire, will have 
just finished expelling a charge of burned gas, and will 
be starting the intake stroke. This timing relates to a 
four-cylinder engine in order to simplify the explanation. 
The timing instructions given apply only to the conven- 
tional motor types. Eotary cylinder engines, especially 
the Gnome "monosoupape," have a distinctive valve 
timing on account of the peculiarities of design. 

GNOME "mONOSOUPAPe" VALVE TIMING 

In the present design of the Gnome motor, a cycle of 
operations somewhat different from that employed in the 
ordinary four-cycle engine is made use of, says a writer 
in "The Automobile, ' ' in describing the action of this 
power-plant. This cycle does away with the need for the 
usual inlet valve and makes the engine operable with only 
a single valve, hence the name monosoupape, or " single- 
valve.' ' The cycle is as follows: A charge being com- 
pressed in the outer end of the cylinder or combustion 
chamber, it is ignited by a spark produced by the spark- 
plug located in the side of this chamber, and the burning 
charge expands as the piston moves down in the cylinder 
while the latter revolves around the crank-shaft. When 



Gnome Monosoupape Timing 279 

the piston is about half-way down on the power stroke, 
the exhanst valve, which is located in the center of the 
cylinder-head, is mechanically opened, and during the 
following upstroke of the piston the burnt gases are 
expelled from the cylinder through the exhaust valve 
directly into the atmosphere. 

Instead of closing at the end of the exhaust stroke, 
or a few degrees thereafter, the exhaust valve is held 
open for about two-thirds of the following inlet stroke 
of the piston, with the result that fresh air is drawn 
through the exhaust valve into the cylinder. "When the 
cylinder is still 65 degrees from the end of the inlet half- 
re volution, the exhaust valve closes. As no more air 
can get into the cylinder, and as the piston continues to 
move inwardly, it is obvious that a partial vacuum is 
formed. 

When the cylinder approaches within 20 degrees of 
the end of the inlet half -revolution a series of small 
inlet ports all around the circumference of the cylinder 
wall is uncovered by the top edge of the piston, whereby 
the combustion chamber is placed in communication with 
the crank chamber. As the pressure in the crank chamber 
is substantially atmospheric and that in the combustion 
chamber is below atmospheric, there results a suction 
effect which causes the air from the crank chamber to 
flow into the combustion chamber. The air in the crank 
chamber is heavily charged with gasoline vapor, which 
is due to the fact that a spray nozzle connected with the 
gasoline supply tank is located inside the chamber. The 
proportion of gasoline vapor in the air in the crank 
chamber is several times as great as in the ordinary 
combustible mixture drawn from a carburetor into the 
cylinder. This extra-rich mixture is diluted in the com- 
bustion chamber with the air which entered it through 
the exhaust valve during the first part of the inlet stroke, 
thus forming a mixture of the proper proportion for 
complete combustion. 

The inlet ports in the cylinder wall remain open until 



280 Aviation Engines 

20 degrees of the compression half-revolution has been 
completed, and from that moment to near the end of the 
compression stroke the gases are compressed in the 
cylinder. Near the end of the stroke ignition takes place 
and this completes the cycle. 

The exact timing of the different phases of the cycle 
is shown in the diagram at Fig. 111. It will be seen that 
ignition occurs substantially 20 degrees ahead of the 
outer dead center, and expansion of the burning gases 
continues until 85 degrees past the outer dead center, 
when the pistbn is a little past half-stroke. Then the 
exhaust-valve opens and remains open for somewhat 
more than a complete revolution of the cylinders, or, to 
be exact, for 390 degrees of cylinder travel, until 115 
degrees past the top dead center on the second revolution. 
Then for 45 degrees of travel the charge within the 
cylinder is expanded, whereupon the inlet ports are un- 
covered and remain open for 40 degrees of cylinder 
travel, 20 degrees on each side of the inward dead center 
position. 

SPKINGLESS VALVES 

Springless valves are the latest development on French 
racing car engines, and it is possible that the positively- 
operated types will be introduced on aviation engines 
also. Two makes of positively-actuated valves are shown 
at Fig. 6. The positive- valve motor differs from the con- 
ventional form by having no necessity for valve-springs, 
as a cam not only assures the opening of the valve, but 
also causes it to return to the valve-seat. In this respect 
it is much like the sleeve-valve motor, where the uncover- 
ing of the ports is absolutely positive. The cars equipped 
with these valves were a success in long-distance auto 
races. Claims made for this type of valve mechanism 
include the possibility of a higher number of revolutions 
and consequently greater engine power. With the spring- 
controlled, single-cam operated valve a point is reached 
where the spring is not capable of returning the valve 



Springless Valves 



281 



to its seat before the cam lias again begun its opening 
movement. It is possible to extend the limits consider- 
ably by using a light valve on a strong spring, but the 




Fig. 111. — Timing Diagram Showing Peculiar Valve Timing of Gnome 
"Monosoupape" Rotary Motor. 



valve still remains a limiting factor in the speed of the 
motor. 

A part sectional view through a cylinder of an engine 
designed by G. Michaux is shown at Fig. 112, A. There 
are two valves per cylinder, inclined at about ten degrees 
from the vertical. The valve-stems are of large diameter, 
as owing to positive control, there is no necessity of 
lightening this part in an unusual degree. A single over- 



282 



Aviation Engines 



head cam-shaft has eight pairs of cams, which are shown 
in detail at B. For each valve there is a three-armed 
rocker, one arm of which is connected to the stem of the 
valve and the two others are in contact respectively with 
the opening and closing cams. The connection to the 
end of the valve-stem is made by a short connecting link, 
which is screwed on to the end of the valve-stem and 



Valve 
Operating 
Bell Crank 



Yoke 
Guide 



Cam Shaft 

Housing 

5upporis 




Va/vea 



Fig. 112. — Two Methods of Operating Valves by Positive Cam Mechanism 
Which Closes as Well as Opens Them. 

locked in position. This allows some adjustment to be 
made between the valves and the actuating rocker. It will 
be evident that one cam and one rocker arm produce 
the opening of the valve and that the corresponding 
rocker arm and cam result in the closing of the valve. 
If the opening cam has the usual convex profile, the clos- 
ing cam has a correspondingly concave profile. It will 
be noticed that a light valve-spring is shown in drawing. 
This is provided to give a final seating to its valve after 



Positive Valve Systems 283 

it has been closed by the cam. This is not absolutely 
necessary, as an engine has been run successfully with- 
out these springs. The whole mechanism is contained 
within an overhead aluminum cover. 

The positive-valve system used on the De Lage motor 
is shown at D. In this the valves are actuated as shown 
in sectional views D and E. The valve system is unique- 
in that four valves are provided per cylinder, two for 
exhaust and two for intake. The valves are mounted 
side by side, as shown at E, so the double actuator mem- 
ber may be operated by a single set of cams. The valve- 
operating member consists of a yoke having guide bars 
at the top and bottom. The actuating cam works inside 
of this yoke. The usual form of cam acts on the lower 
portion of the yoke to open the valve, while the concave 
cam acts on the upper part to close the valves. In this 
design provision is made for expansion of the valve-stems 
due to heat, and these are not positively connected to the 
actuating member. As shown at E, the valves are held 
against the seat by short coil springs at the upper end 
of the stem. These are very stiff and are only intended 
to provide for expansion. A slight space is left between 
the top of the valve- stem and the portion of the operat- 
ing member that bears against them when the regular 
profile cam exerts its pressure on the bottom of the valve- 
operating mechanism. Another novelty in this motor 
design is that the cam-shafts and the valve-operating 
members are carried in casing attached above the motor 
by housing supports in the form of small steel pillars. 
The overhead cam-shafts are operated by means of bevel 
gearing. 

FOUR VALVES PER CYLINDER 

Mention has been previously made of the sixteen- 
valve four-cylinder Duesenberg motor and its great power 
output for the piston displacement. This is made pos- 
sible by the superior volumetric efficiency of a motor 
provided with four valves in each cylinder instead of 



284 



Aviation Engines 



but two. This principle was thoroughly tried out in rac- 
ing automobile motors, and is especially valuable in per- 
mitting of greater speed and power output from simple 
four- and six-cylinder engines. On eight- and twelve- 
cylinder types, it is doubtful if the resulting complica- 
tion due to using a very large number of valves would 
•be worth while. When extremely large valves are used, 



Two Small 
Valves 




One Large 
Valve 



Fig. 113. — Diagram Comparing Two Large Valves and Four Small Ones 
of Practically the Same Area. Note How Easily Small Valves are 
Installed to Open Directly Into the Cylinder. 



as shown in diagram at Fig. 113, it is difficult to have 
them open directly into the cylinder, and pockets are 
sometimes necessary. A large valve would weigh more 
than two smaller valves having an area slightly larger 
in the aggregate; it would require a stifTer valve spring 
on account of its greater weight. A certain amount of 
metal in the valve-head is necessary to prevent warping; 
therefore, the inertia ' forces will be greater in the large 
valve than in the two smaller valves. As a greater port 



Multiple Valve Advantages 



285 




286 



Aviation Engines 



area is obtained by the use of two valves, the gases will 
be drawn into the cylinder or expelled faster than with 
a lesser area. Even if the areas are practically the same 
as in the diagram at Fig. 113, the smaller valves may 



Inlet Valve Depressing Lever 
,Spark Plug 
I 



,Push Rod 



Inlet Valve 



Jnlet Valve 



Exhaust Valve 
Actuating 
Lever, 



Pull Tube 




Cylinder 



>ul\ Tube / 
Spr ' 



'Cylinder hold 
down Bolts 



Propeller Hub 



Oil Gauge -— 



Oil Pump 



Tig. 115. — Front View of Curtiss 0X3 Aviation Motor, Showing Uncon- 
ventional Valve Action by Concentric Push Rod and Pull Tube. 



have a greater lift without imposing greater stresses on 
the valve-operating mechanism and quicker gas intake 
and exhaust obtained. The smaller valves are not af- 
fected by heat as much as larger ones are. The quicker 
gas movements made possible, as well as reduction of 



Multiple Valve Advantages 287 

inertia forces, permits of higher rotative speed, and, 
consequently, greater power output for a given piston 
displacement. The drawings at Fig. 114 show a sixteen- 
valve motor of the four-cylinder type that has been de- 
signed for automobile racing purposes, and it is apparent 
that very slight modifications would make it suitable for 
aviation purposes. Part of the efficiency is due to the 
reduction of bearing friction by the use of ball bearings, 
but the multiple-valve feature is primarily responsible 
for the excellent performance. 



CHAPTER IX 

Constructional Details of Pistons — Aluminum Cylinders and Pistons — 
Piston Ring Construction — Leak Proof Piston Rings — Keeping 
Oil Out of Combustion Chamber — Connecting Rod Forms — Con- 
necting Rods for Vee Engines — Cam-Shaft and Crank-Shaft De- 
signs — Ball Bearing Crank-Shafts — Engine Base Construction. 

CONSTRUCTIONAL DETAILS OF PISTONS 

The piston is one of the most important parts of the 
gasoline motor inasmuch as it is the reciprocating mem- 
ber that receives the impact of the explosion and which 
transforms the power obtained by the combustion of gas 
to mechanical motion by means of the connecting rod to 
which it is attached. The piston is one of the simplest 
elements of the motor, and it is one component which 
does not vary much in form in different types of motors. 
The piston is a cylindrical member provided with a series 
of grooves in which packing rings are placed on the out- 
side and two bosses which serve to hold the wrist pin in 
its interior. It is usually made of cast iron or aluminum, 
though in some motors where extreme lightness is de- 
sired, such as those used for aeronautic work, it may be 
made of steel. The use of the more resisting material 
enables the engineer to use lighter sections where it is 
important that the weight of this member be kept as low 
as possible consistent with strength. 

A number of piston types are shown at Fig. 116. That 
at A has a round top and is provided with four split 
packing rings and. two oil grooves. A piston of this type 
is generally employed in motors where the combustion 
chamber is large and where it is desired to obtain a 
higher degree of compression than would be possible with 
a flat top piston. This construction is also stronger be- 
cause of the arched piston top. The most common form 

288 



Constructional Details of Pistons 



289 



of piston is that shown at B, and it differs from that 
previously described only in that it has a flat top. The 
piston outlined in section at C is a type used on some 
of the sleeve-valve motors of the Knight pattern, and 
has a concave head instead of the convex form shown 
at A. The design shown at D in side and plan views is 




\ 


o 


II 


■ii nil 



Side View 



Fig. 116. — Forms of Pistons Commonly Employed in Gasoline Engines. 
A — Dome Head Piston and Three Packing Rings. B — Flat Top Form 
Almost Universally Used. C — Concave Piston Utilized in Knight 
Motors and Some Having Overhead Valves. D — Two-Cycle Engine 
Member with Deflector Plate Cast Integrally. E — Differential of 
Two-Diameter Piston Used in Some Engines Operating on Two-Cycle 
Principle. 



the conventional form employed in two-cycle engines. 
The deflector plate on the top of the cylinder is cast in- 
tegral and is utilized to prevent the incoming fresh gases 
from flowing directly over the piston top and out of the 
exhaust port, which is usually opposite the inlet open- 
ing. On these types of two-cycle engines where a two- 
diameter cylinder is employed, the piston shown at E is 



290 



Aviation Engines 




4^ 




vjjg4 Wl f g////m,,,,,,,„,,>t>>»>,A 






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QD 



vmmm 



ft- 



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£ *? « 
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Li +3 v. rt p 



02 02 p. 



bb 



Constructional Details of Pistons 



291 



used. This is known as a "differential piston," and has 
an enlarged portion at its lower end which fits the pump- 
ing cylinder. The usual form of deflector plate is pro- 



Wrist Pin 
Boss 




Connecting Rod- 



Connecting Rod Bearing, 



Bearing Liner's 
Connecting Rod Cap 



Connecting Rod Bolts 




Oil Scoop 



Fig. 118. — Typical Piston and Connecting Rod Assembly. 



vided at the top of the piston and one may consider it 
as two pistons in one. 

One of the important conditions in piston design is 
the method of securing the wrist pin which is used to 



292 



Aviation Engines 



connect the piston to the upper end of the connecting 
rod. Various methods have been devised to keep the 
pin in place, the most common of these being shown at 
Fig. 117. The wrist pin should be retained by some 
positive means which is not liable to become loose under 
the vibratory stresses which obtain at this point. If the 



Spark PI 



Spark 
Plug 




Connecting Rod 
Big End Boxes 



Pis -to n 

Rings~.?\ 



Fig. 119. — Parts of Sturtevant Aviation Engine. A — Cylinder Head 
Showing Valves. B — Connecting Rod. C — Piston and Rings. 



Constructional Details of Pistons 



293 



wrist pin was free to move it would work out of the 
bosses enough so that the end would bear against the 
cylinder wall. As it is usually made of steel, which is a 
harder material than cast iron used in cylinder construc- 
tion, the rubbing action would tend to cut a groove in 
the cylinder wall which would make for loss of power 




Fig. 120. — Aluminum Piston and Light But Strong Steel Connecting Rod 
and Wrist Pin of Thomas Aviation Engine. 



because it would permit escape of gas. The wrist pin 
member is a simple cylindrical element that fits the bosses 
closely, and it may be either hollow or solid stock. A 
typical piston and connecting rod assembly which shows 
a piston in section also is given at Fig. 118. The piston 
of the Sturtevant aeronautical motor is shown at Fig. 
119, the aluminum piston of the Thomas airplane motor 
with piston rings in place is shown at Fig. 120. A good 
view of the wrist pin and connecting rod are also given. 
The iron piston of the Gnome "Monosoupape" airplane 
engine and the unconventional connecting rod assembly 
are clearly depicted at Fig 121. 

The method of retention shown at A is the simplest 
and consists of a set screw having a projecting portion 



294 



Aviation Engines 



passing into the wrist pin and holding it in place. The 
screw is kept from turning or loosening by means of a 
check nut. The method outlined at B is similar to that 
shown at A, except that the wrist pin is solid and the 
point of the set screw engages an annular groove turned 
in the pin for its reception. A very positive method is 
shown at C. Here the retention screws pass into the 
wrist pin and are then locked by a piece of steel wire 
which passes through suitable holes in the ends. The 
method outlined at D is sometimes employed, and it varies 




Fig. 121. — Cast Iron Piston of "Monosoupape" Gnome Engine Installed 
On One of the Short Connecting Rods. 



from that shown at C only in that the locking wire, which 
is made of spring steel, is passed through the heads of 
the locking screws. Some designers machine a large 
groove around the piston at such a point that when the 
wrist pin is put in place a large packing ring may be 
sprung in the groove and utilized to hold the wrist pin 
in place. 

The system shown at F is not so widely used as the 
simpler methods, because it is more costly and does not 
offer any greater security when the parts are new than 
the simple lock shown at A. In this a hollow wrist pin is 
used, having a tapered thread cut at each end. The wrist 
pin is slotted at three or four points, for a distance equal 
to the length of the boss, and when taper expansion plugs 



Piston Pin Retention 295 

are screwed in place the ends of the wrist pin are ex- 
panded against the bosses. This method has the advan- 
tage of providing a certain degree of adjustment if the 
wrist pin shonld loosen np after it has been in use for 
some time. The taper pings would be screwed in deeper 
and the ends of the wrist pin expanded proportionately 
to take up the loss motion. The method shown at G is 
an ingenious one. One of the piston bosses is provided 
with a projection which is drilled out to receive a plunger. 
The wrist pin is provided with a hole of sufficient size to 
receive the plunger, which is kept in place by means of 
a spring in back of it. This makes a very positive lock 
and one that can be easily loosened when it is desired to 
remove the wrist pin. To unlock, a piece of fine rod is 
thrust into the hole at the bottom of the boss which pushes 
the plunger back against the spring until the wrist pin 
can be pushed out of the piston. 

Some engineers think it advisable to oscillate the wrist 
pin in the piston bosses, instead of in the connecting rod 
small end. It is argued that this construction gives more 
bearing surface at the wrist pin and also provides for 
more strength because of the longer bosses that can be 
used. AVhen this system is followed the piston pin is 
held in place by locking it to the connecting rod by some 
means. At H the simplest method is outlined. This con- 
sisted of driving a taper pin through both rod and wrist 
pin and then preventing it from backing out by putting 
a split cotter through the small end of the tapered lock- 
ing pin. Another method, which is depicted at I, consists 
of clamping the wrist pin by means of a suitable bolt 
which brings the slit connecting rod end together as 
shown. 

ALUMINUM FOK CYLINDEKS AND PISTONS 

Aluminum pistons outlined at Fig. 122, have replaced 
cast iron members in many airplane engines, as these 
weigh about one-third as much as the cast iron forms of 
the same size, while the reduction in the inertia forces 



296 



Aviation Engines 



has made it possible to increase the engine speed without 
correspondingly stressing the connecting rods, crank-shaft 
and engine bearings. 

Aluminum has not only been used for pistons, but a 
number of motors will be built for the coming season that 
will use aluminum cylinder block castings as well. Of 
course, the aluminum alloy is too soft to be used as a 
bearing for the piston, and it will not withstand the ham- 
mering action of the valve. This makes the use of cast 




■Ribs 



Ra clng 
Piston 



/Hourglass 
\ Piston 




^'Recesses in Casting 
Hourglass Piston., 



.Ribs for Strength and 
i Heat Radiation* 





9«®©®ii!? 



ww/j r/////// 

'' Wrist Pin' 
Bosses 



Wrist Pin Boss-' 



Sections of Aluminum Piston 



Fig. 122. — Types of Aluminum Pistons Used In Aviation Engines. 

iron or steel imperative in all motors. When used in con- 
nection with an aluminum cylinder block the cast iron 
pieces are placed in the mould so that they act as cylinder 
liners and valve seats, and the molten metal is poured 
around them when the cylinder is cast. It is said that 
this construction results in an intimate bond between the 
cast iron and the surrounding aluminum metal. Steel 
liners may also be pressed into the aluminum cylinders 
after these are bored out to receive them. Aluminum 
has for a number of years been used in many motor 



Aluminum Pistons 297 

car parts. Alloys have been developed that have greater 
strength than cast iron and that are not so brittle. Its 
use for manifolds and engine crank and gear cases has 
been general for a number of years. 

At first thought it would seem as though aluminum 
would be entirely unsuited for use in those portions of 
internal combustion engines exposed to the heat of the 
explosion, on account of the low melting point of that 
metal and its disadvantageous quality of suddenly "wilt- 
ing" when a critical point in the temperature is reached. 
Those who hesitated to use aluminum on account of this 
defect lost sight of the great heat conductivity of that 
metal, which is considerably more than that of cast iron. 
It was found in early experiments with aluminum pistons 
that this quality of quick radiation meant that aluminum 
pistons remained considerably cooler than cast iron ones 
in service, which was attested to by the reduced forma- 
tion of carbon deposits thereon. The use of aluminum 
makes possible a marked reduction in power plant weight. 
A small four-cylinder engine which was not particularly 
heavy even with cast iron cylinders was found to weigh 
100 pounds less when the cylinder block, pistons, and 
upper half of the crank-case had been made of aluminum 
instead of cast iron. Aluminum motors are no longer 
an experiment, as a considerable number of these have 
been in use on cars during the past year without the 
owners of the cars being apprised of the fact. Absolutely 
no complaint was made in any case of the aluminum 
motor and it was demonstrated, in addition to the saving 
•in weight, that the motors cost no more to assemble and 
cooled much more efficiently than the cast iron form. One 
of the drawbacks to the use of aluminum is its growing 
scarcity, which results in making it a "near precious" 
metal. 

PISTON RING CONSTRUCTION 

As all pistons must be free to move up and down in 
the cylinder with minimum friction, they must be less in 



298 Aviation Engines 

diameter than the bore of the cylinder. The amount of 
freedom or clearance provided varies with the construc- 
tion of the engine and the material the piston is made of, 
as well as its size, but it is usual to provide from .005 to 
.010 of an inch to compensate for the expansion of the 
piston due to heat and also to leave sufficient clearance 
for the introduction of lubricant between the working 
surfaces. Obviously, if the piston were not provided with 
packing rings, this amount of clearance would enable a 
portion of the gases evolved when the charge is exploded 
to escape by it into the engine crank-case. The packing 






o 


( B 






r~ 


"-I1 1 




G 


] c 


1 




D 


/ c 


^r 1 




£ 



Fig. 123. — Types of Piston Kings and Ring Joints. A — Concentric Ring. 
B — Eccentrically Machined Form. C — Lap Joint Ring. D — Butt Joint, 
Seldom Used. E — Diagonal Cut Member, a Popular Form. 

members or piston rings, as they are called, are split 
rings of cast iron, which are sprung into suitable grooves 
machined on the exterior of the piston, three or four of 
these being the usual number supplied. These have suffi- 
cient elasticity so that they bear tightly against the cylin- 
der wall and thus make a gas-tight joint. Owing to the 
limited amount of surface in contact with the cylinder 
wall and the elasticity of the split rings the amount of 
friction resulting from the contact of properly fitted rings 
and the cylinder is not of enough moment to cause any 
damage and the piston is free to slide up and down in 
the cylinder bore. 

These rings are made in two forms, as outlined at 
Fig. 123. The design shown at A is termed a "concentric 



Piston Ring Forms 299 

ring," because the inner circle is concentric with the 
outer one and the ring is of uniform thickness at all 
points. The ring shown at B is called an "eccentric 
ring," and it is thicker at one part than at others. It 
has theoretical advantages in that it will make a tighter 
joint than the other form, as it is claimed its expansion 
due to heat is more uniform. The piston rings must be 
split in order that they may be sprung in place in the 
grooves, and also to insure that they will have sufficient 
elasticity to take the form of the cylinder at the different 
points in their travel. If the cylinder bore varies by 
small amounts the rings will spring out at the points 
where the bore is larger than standard, and spring in at 
those portions where it is smaller than standard. 

It is important that the joint should be as nearly gas- 
tight as possible, because if it were not a portion of the 
gases would escape through the slots in the piston rings. 
The joint shown at C is termed a "lap joint," because 
the ends of the ring are cut in such a manner that they 
overlap. This is the approved joint. The butt joint 
shown at D is seldom used and is a very poor form, the 
only advantage being its cheapness. The diagonal cut 
shown at E is a compromise between the very good form 
shown at C and the poor joint depicted at D. It is also 
widely used, though most constructors prefer the lap 
joint, because it does not permit the leakage of gas as 
much as the other two types. 

There seems to be some difference of opinion relative 
to the best piston ring type — some favoring the eccentric 
pattern, others the concentric form. The concentric ring 
has advantages from the lubricating engineer's point of 
view; as stated by the Piatt & Washburn Company in 
their text-book on engine lubrication, the smaller clear- 
ance behind the ring possible with the ring of uniform 
section is advantageous. 

Fig. 124, A, shows a concentric piston ring in its 
groove. Since the ring itself is concentric with the 
groove, very small clearance between the back of the ring 



300 



Aviation Engines 



and the bottom of its groove may be allowed. Small 
clearance leaves less space for the accumulation of oil 
and carbon deposits. The gasket effect of this ring is 
uniform throughout the entire length of its edges, which 
is its marked advantage over the eccentric ring. This 
type of piston ring rarely burns fast in its groove. There 
are a large number of different concentric rings manu- 
factured of different designs and of different efficiency. 
Figs. 124, B and 124, C show eccentric rings assembled 
in the ring groove. It will be noted that there is a large 



Cylinder^ ^Clearance 
/Ring 



.Clearana 



Cylindi 



Clearance- 




Watery 

Jacket 



Eccentric Ring- 

c 



Fig. 124. — Diagrams Showing Advantages of Concentric Piston Rings. 



space between the thin ends of this ring and the bottom 
of the groove. This empty space fills up with oil which 
in the case of the upper ring frequently is carbonized, 
restricting the action of the ring and nullifying its use- 
fulness. The edges of the thin ends are not sufficiently 
wide to prevent rapid escape of gases past them. In a 
practical way this leakage means loss of compression and 
noticeable drop in power. When new and properly fitted, 
very little difference can be noted between the tightness 
of eccentric and concentric rings. Nevertheless, after 
several months' use, a more rapid leakage will always 
occur past the eccentric than past the concentric. If 
continuous trouble with the carbonization of cylinders, 
smoking and sooting of spark-plugs is experienced,- it is 



Leak-Proof Piston Rings 301 

a sure indication that mechanical defects exist in the en- 
gine, assuming of course, that a suitable oil has been 
used. Such trouble can be greatly lessened, if not en- 
tirely eliminated, by the application of concentric rings 
(lap joint), of any good make, properly fitted into the 
grooves of the piston. Too much emphasis cannot be 
put upon this point. If the oil used in the engine is of 
the correct viscosity, and serious carbon deposit, smoking, 
etc., still result, the only certain remedy then is to have 
the cylinders rebored and fitted with properly designed, 
oversized pistons and piston rings. 

LEAK-PROOF PISTON RINGS 

In order to reduce the compression loss and leakage 
of gas by the ordinary simple form of diagonal or lap 
joint one-piece piston ring a number of compound rings 
have been devised and are offered by their makers to 
use in making replacements. The leading forms are 
shown at Fig. 125. That shown at A is known as the 
"Statite" and consists of three rings, one carried inside 
while the other two are carried on the outside. The ring 
shown at B is a double ring and is known as the McCad- 
den. This is composed of two thin concentric lap joint 
rings so disposed relative to each other that the opening 
in the inner ring comes opposite to the opening in the 
outer ring. 

The form shown at C is known as the "Leektite," 
and is a single ring provided with a peculiar form of lap 
and dove tail joint. The ring shown at D is known as 
the " Dunham' ' and is of the double concentric type being 
composed of two rings with lap joints which are welded 
together at a point opposite the joint so that there is no 
passage by which the gas can escape. The Burd high 
compression ring is shown at E. The joints of these 
rings are sealed by means of an H-shaped coupler of 
bronze which closes the opening. The ring ends are made 
with tongues which interlock with the coupling. The 



302 



Aviation Engines 



ring shown at F is called the "Evertite" and is a three- 
piece ring composed of three members as shown in the 
sectional view below the ring. The main part or inner 
ring has a circumferential channel in which the two outer 
rings lock, the resulting cross-section being rectangular 
just the same as that of a regular pattern ring. All 
three rings are diagonally split and the joints are spaced 
equally and the distances maintained by small pins. This 




Fig. 125. — Leak-Proof and Other Compound Piston Rings. 



results in each joint being sealed by the solid portion of 
the other rings. 

The use of a number of light steel rings instead of 
one wide ring in the groove is found on a number of 
automobile power plants, but as far as known, this con- 
struction is not used in airplane power plants. It is 
contended that where a number of light rings is em- 
ployed a more flexible packing means is obtained and the 
possibility of leakage is reduced. Eings of this design 
are made of square section steel wire and are given a 
spring temper. Owing to the limited width the diagonal 



Keeping Oil Out of Combustion Chambers 303 

cut joint is generally employed instead of the lap joint 
which is so popular on wider rings. 



KEEPING OIL OUT OF COMBUSTION CHAMBERS 

An examination of the engine design that is econom- 
ical in oil consumption discloses the use of tight piston 
rings, large centrifugal rings on the crank-shaft where it 
passes through the case, ample cooling fins in the pistons, 
vents between the crank-case chamber and the valve en- 
closures, etc. Briefly put, cooling of the oil in this engine 
has been properly cared for and leakage reduced to a 
minimum. To be specific regarding details of design: 
Oil surplus can be kept out of the explosion chambers by 
leaving the lower edge of the piston skirt sharp and by 
the use of a shallow groove (C), Fig. 126, just below the 
lower piston ring. Small holes are bored through the 
piston walls at the base of this groove and communicate 
with the crank-case. The similarity of the sharp edges 
of piston skirt (D) and piston ring to a carpenter's plane 
bit, makes their operation plain. 

The cooling of oil in the sump (A) can be accom- 
plished most effectively by radiating fins on its outer 
surface. The lower crank-case should be fully exposed to 
the outer air. A settling basin for sediment (B) should 
be provided having a cubic content not less than one- 
tenth of the total oil capacity as outlined at Fig. 126. 
The depth of this basin should be at least 2y 2 inches, and 
its walls vertical, as shown, to reduce the mixing of sedi- 
ment with the oil in circulation. The inlet opening to 
the oil pump should be near the top of the sediment basin 
in order to prevent the entrance into the pump with the 
oil of any solid matter or water condensed from the prod- 
ucts of combustion. This sediment basin should be 
drained after every five to seven hours air service of an 
airplane engine. Concerning filtering screens there is 
little to be said, save that their areas should be ample 
and the mesh coarse enough (one-sixteenth of an inch) to 



304 



Aviation Engines 



offer no serious resistance to the free flow of cold or 
heavy oil through them; otherwise the oil in the crank- 
case may build up above them to an undesirable level. 
The necessary frequency of draining and flushing out the 
oil sump differs greatly with the age (condition) of the 




^Sediment Basin 



Fig. 126. — Sectional View of Engine Showing Means of Preventing 
Oil Leakage By Piston Rings. 



engine and the suitability of the oil used. In broad terms, 
the oil sump of a new engine should be thoroughly drained 
and flushed with kerosene at the end of the first 200 



Connecting Rod Forms 305 

miles, next at the end of 500 miles and thereafter every 
1,000 miles. "While these instructions apply specifically 
to automobile motors, it is very good practice to change 
the oil in airplane engines frequently. In many cases, 
the best results have been secured when the oil supply 
is completely replenished every five hours that the en- 
gine is in operation. 



COXXECTIXG ROD FORMS 

The connecting rod is the simple member that joins 
the piston to the crank-shaft and which transmits the 
power imparted to the piston by the explosion so that it 
may be usefully applied. It transforms the reciprocating 
movement of the piston to a rotary motion at the crank- 
shaft. A typical connecting rod and its wrist pin are 
shown at Fig. 120. It will be seen that it has two bear- 
ings, one at either end. The small end is bored out to 
receive the wrist pin which joins it to the piston, while 
the large end has a hole of sufficient size to go on the 
crank-pin. The airplane and automobile engine connect- 
ing rod is invariably a steel forging, though in marine 
engines it is sometimes made a steel or high tensile 
strength bronze casting. In all cases it is desirable to 
have softer metals than the crank-shaft and wrist pin at 
the bearing point, and for this reason the connecting rod 
is usually provided with bushings of anti-friction or white 
metal at the lower end, and bronze at the upper. The 
upper end of the connecting rod may be one piece, be- 
cause the wrist pin can be introduced after it is in place 
between the bosses of the piston. .The lower bearing- 
must be made in two parts in most cases, because the 
crank- shaft cannot be passed through the bearing o wing- 
to its irregular form. The rods of the Gnome engine are 
all one piece types, as shown at Fig. 127, owing to the 
construction of the "mother" rod which receives the 
crank-pins. The complete connecting rod assembly is 
shown in Fig. 121, also at A, Fig. 127. The "mother" 



306 



Aviation Engines 



rod, with one of the other rods in place and one about 
to be inserted, is shown at Fig. 127, B. The built-up 
crank-shaft which makes this construction feasible is 
shown at Fig. 127, B. 

Some of the various designs of connecting rods that 
have been used are shown at Fig. 128. That at A is a 
simple form often employed in single-cylinder motors, 
having built-up crank-shafts. Both ends of the connect- 




ihuiuuuumiuiuunUi 



c 



Fig. 127. — Connecting Rod and Crank-Shaft Construction of Gnome 
"Monosoupape" Engine. 



ing rod are bushed with a one-piece bearing, as it can 
be assembled in place before the crank-shaft assembly is 
built up. A built-up crank-shaft such as this type of con- 
necting rod would be used with is shown at Fig. 106. The 
pattern shown at B is one that has been used to some 
extent on heavy work, and is known as the "marine 
type." It is made in three pieces, the main portion being 
a steel forging having a flanged lower end to which the 
bronze boxes are secured by bolts. The modified marine 
type depicted at C is the form that has received the wid- 
est application in automobile and aviation engine con- 



Connecting Rod Forms 



307 




*8°3 

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308 Aviation Engines 

struction. It consists of two pieces, the main member 
being a steel drop forging having the wrist-pin bearing 
and the upper crank-pin bearing formed integral, while 
the lower crank-pin bearing member is a separate forg- 
ing secured to the connecting rod by bolts. In this con- 
struction bushings of anti-friction metal are used at the 
lower end, and a bronze bushing is forced into the upper- 
or wrist-pin end. The rod shown at D has also been 
widely used. It is similar in construction to the form 
shown at C, except that the upper end is split in order 
to permit of a degree of adjustment of the wrist-pin 
bushing, and the lower bearing cap is a hinged member 
which is retained by one bolt instead of two. When it is 
desired to assemble it on the crank-shaft the lower cap 
is swung to one side and brought back into place when 
the connecting rod has been properly located. Sometimes 
the lower bearing member is split diagonally instead of 
horizontally, such a construction being outlined at E. 

In a number of instances, instead of plain bushed 
bearings anti-friction forms using ball or rollers have 
been used at the lower end. A ball-bearing connecting 
rod is shown at F. The big end may be made in one 
piece, because if it is possible to get the ball bearing on 
the crank-pins it will be easy to put the connecting rod 
in place. Ball bearings are not used very often on con- 
necting rod big. ends because of difficulty of installation, 
though when applied properly they give satisfactory serv- 
ice and reduce friction to a minimum. One of the ad- 
vantages of the ball bearing is that it requires no adjust- 
ment, whereas the plain bushings depicted in the other 
connecting rods must be taken up from time to time to 
compensate for wear. 

This can be done in forms shown at B, C, D, and E 
by bringing the lower bearing caps closer to the upper 
one and scraping out the brasses to fit the shaft. A 
number of liners or shims of thin brass or copper stock, 
varying from .002 inch to .005 inch, are sometimes inter- 
posed between the halves of the bearings when it is first 



Connecting Rod Types 



309 



fitted to the crank-pin. As the brasses wear the shims 
may be removed and the portions of the bearings brought 
close enough together to take up any lost motion that 
may exist, though in some motors no shims are provided 
and depreciation can be remedied only by installing new 
brasses and scraping to fit. 

The various structural shapes in which connecting rods 
are formed are shown in section at Gr. Of these the I 





)£pRing Grooves 








-Piston 




III 


^v- 


^Piston Pin 
M> Oil Drain Holes 


Piston Pin Bushing 


Oil Drain -"-"""^ %^ > 
Holes \. -" 








Connecting Rod 
(Blade) 




\\ \ Bolts 


ff -ffir Connecting Rod 
'/ /jf (Forked) 




Cap- 




^-Connecting Rod Bearing 






wLxs: JJ < 


rCap 






'^P^X 





Fig. 129. — Double Connecting Rod Assembly For Use On Single Crank- 
Pin of Vee Engine. 



section is most widely used in airplane engines, because 
it is strong and a very easy shape to form by the drop- 
forging process or to machine out of the solid bar when 
extra good steel is used. Where extreme lightness is 
desired, as in small high-speed motors used for cycle pro- 
pulsion, the section shown at the extreme left is often 
used. If the rod is a cast member as in some marine en- 
gines, the cross, hollow cylinder, or U sections are some- 
times used. If the sections shown at the right are em- 



310 



Aviation Engines 



ployed, advantage is often taken of the opportunity for 
passing lubricant through the center of the hollow round 
section on vertical motors or at the bottom of the U 
section, which would be used on a horizontal cylinder 
power plant. 

Connecting rods of Vee engines are made in two dis- 
tinct styles. The forked or "scissors" joint rod assembly 




Fig. 130. — Another Type of Double Connecting Rod for Vee Engines. 



is employed when the cylinders are placed directly op- 
posite each other. The "blade" rod, as shown at Fig. 
129, fits between the lower ends of the forked rod, which 
oscillate on the bearing which encircles the crank-pin. 
The lower end of the "blade" rod is usually attached to 
the bearing brasses, the ends of the "forked" rod move 
on the outer surfaces of the brasses. Another form of 
rod devised for use under these conditions is shown at 
Fig. 130 and installed in an aviation engine at Fig. 132. 
In this construction the shorter rod is attached to a boss 
on the master rod by a short pin to form a hinge and to 
permit the short rod to oscillate as the conditions die- 



Connecting Rod Types 



311 




312 



Aviation Engines 



tate. This form of rod can be easily adjusted when the 
bearing depreciates, a procedure that is difficult with the 
forked type rod. The best practice, in the writer 's opin- 




Fig. 132. — Part Sectional View of Renault Twelve-Cylinder Water-Cooled 
Engine, Showing Connecting Rod Construction and Other Important 
Internal Parts. 



ion, is to stagger the cylinders and use side-by-side rods 
as is done in the Curtiss engine. Each rod may be fitted 
independently of the other and perfect compensation for 
wear of the big ends is possible. 



Cam- Shaft and Crank- Shaft Design 313 

CAM-SHAFT AND CRANK-SHAFT DESIGN 

Before going extensively into the subject of crank- 
shaft construction it will be well to consider cam-shaft 
design, which is properly a part of the valve system and 
which has been considered in connection with the other 
elements which have to do directly with cylinder construc- 
tion to some extent. Cam-shafts are usually simple mem- 
bers carried at the base of the cylinder in the engine 
case of Vee type motors by suitable bearings and having 
the cams employed to lift the valves attached at intervals. 
A typical cam-shaft design is shown at Fig. 133. Two 
main methods of cam-shaft construction are followed — 




Fig. 133. — Typical Cam-Shaft, with Valve Lifting Cams and Gears to 
Operate Auxiliary Devices Forged Integrally. 

that in which the cams are separate members, keyed and 
pinned to the shaft, and the other where the cams are 
formed integral, the latter being the most suitable for 
airplane engine requirements. 

The cam-shafts shown at Figs. 133 and 134, B, are of 
the latter type, as the cams are machined integrally. In 
this case not only the cams but also the gears used in 
driving the auxiliary shafts are forged integral. This is 
a more expensive construction, because of the high initial 
cost of forging dies as well as the greater expense of 
machining. It has the advantage over the other form in 
which the cams are keyed in place in that it is stronger, 
and as the cams are a part of the shaft they can never 
become loose, as might be possible where they are sepa- 
rately formed and assembled on a simple shaft. 

The importance of the crank-shaft has been previously 



314 



Aviation Engines 



considered, and some of its forms have been shown in 
views of the motors presented in earlier portions of this 
work. The crank-shaft is one of the parts subjected to 
the greatest strain and extreme care is needed in its con- 




££■>« ML 



^pu® 



Fig. 134. — Important Parts of Duesenberg Aviation Engine. A — Three 
Main Bearing Crank-Shaft. B — Cam-Shaft with Integral Cams. C — 
Piston and Connecting Rod Assembly. D — Valve Rocker Group. 
E — Piston. F — Main Bearing Brasses. 



struction and design, because practically the entire duty 
of transmitting the power generated by the motor to the 
gearset devolves upon it. Crank-shafts are usually made 
of high tensile strength steel of special composition. They 
may be made in four ways, the most common being from 



Crank-Shaft Construction 



315 



a drop or machine forging which is formed approximately 
to the shape of the finished shaft and in rare instances 
(experimental motors only) they may be steel castings. 
Sometimes they are made from machine forgings, where 
considerably more machine work is necessary than would 
be the case where the shaft is formed between dies. 
Some engineers favor blocking the shaft out of a solid 
slab of metal and then machining this rough blank to 
form. In some radial-cylinder motors of the Gnome and 




Fig. 135. — Showing Method of Making Crank-Shaft. A — The Rough Steel 
Forging Before Machining. B — The Finished Six-Throw, Seven-Bear- 
ing Crank-Shaft. 

Le Ehone type the crank-shafts are bnilt up of two pieces, 
held together by taper fastenings or bolts. 

The form of the shaft depends on the number of 
cylinders and the form has material influence on the 
method of construction. For instance, a four-cylinder 
crank-shaft could be made by either of the methods out- 
lined. On the other hand, a three- or six-cylinder shaft 
is best made by the machine forging process, because if 
drop forged or cut from the blank it will have to be 
heated and the crank throws bent around so that the pins 
will lie in three planes one hundred and twenty degrees 
apart, while the other types described need no further 
attention, as the crank-pins lie in planes one hundred 
and eighty degrees apart. This can be better understood 
by referring to Fig. 135, which shows a six-cylinder shaft 
in the rough and finished stages. At A the appearance 



316 



Aviation Engines 



of the machine forging before any of the material is re- 
moved is shown, while at B the appearance of the finished 
crank-shaft is clearly depicted. The built-up crank-shaft 
is seldom used on multiple-cylinder motors, except in 




Fig. 



136. — Showing Form of Crank-Shaft for Twin-Cylinder Opposed 
Power Plant. 



some cases where the crank-shafts revolve on ball bear- 
ings as in some automobile racing engines. 

Crank-shaft form will vary with a number of cylinders 
and it is possible to use a number of different arrange- 
ments of crank-pins and bearings for the same number 




Fig. 137. — Crank-Shaft of Thomas-Morse Eight-Cylinder Vee Engine. 



of cylinders. The simplest form of crank- shaft is that 
used on simple radial cylinder motors as it would consist 
of but one crank-pin, two webs, and the crank-shaft. As 
the number of cylinders increase in Vee motors as a gen- 
eral rule more crank-pins are used. The crank- shaft that 



Crank-Shaft Construction 



317 



would be used on a two-cylinder opposed motor is shown 
at Fig. 136. This has two throws and the crank-pins are 
spaced 180 degrees apart. The bearings are exception- 
ally long. Four-cylinder crank-shafts may have two, 
three or five main bearings and three or four crank-pins. 
In some forms of two-bearing crank-shafts, such as used 
when four-cylinders are cast in a block, or unit casting, 




Fig. 138.— Crank-Case and Crank-Shaft Construction for Twelve-Cylinder 
Motors. A — Duesenberg. B — Curtiss. 

two of the pistons are attached to one common crank- 
pin, so that in reality the crank-shaft has but three crank- 
pins. A typical three bearing, four-cylinder crank-shaft 
is shown at Fig. 134, A. The same type can be used for 
an eight-cylinder Vee engine, except for the greater length 
of crank-pins to permit of side by side rods as shown at 
Fig. 137. Six cylinder vertical tandem and twelve-cylin- 
der Vee engine crank-shafts usually have four or seven 
main bearings depending upon the disposition of the 
crank-pins and arrangement of cylinders. At Fig. 138, A, 



318 



Aviation Engines 



the bottom view of a twelve-cylinder engine with bottom 
half of crank case removed is given. This illustrates 
clearly the arrangement of main bearings when the crank- 
shaft is supported on four journals. The crank-shaft 
shown at Fig. 138, B. is a twelve-cylinder seven-bearing 
type. 

In some automobile engines, extremely good results 
have been secured in obtaining steady running with mini- 



/, Balance weights forged 
f V. integrally with shaft 



.Main Bearing No. I 



> Main Bearing No.3 




Main Bearing No,2 y A 

^-"/■Balance weights bolted on 




Balance weighfs 



Fig. 139. — Counterbalanced Crank-Shafts Eeduce Engine Vibration and 
Permit of Higher Rotative Speeds. 



mum vibration by counterbalancing the crank-shafts as 
outlined at Fig. 139. The shaft at A is a type suitable 
for a high speed four-cylinder vertical or an eight-cylin- 
der Vee type. That at B is for a six-cylinder vertical or 
a twelve-cylinder V with scissors joint rods. If counter- 
balancing crank-shafts helps in an automobile engine, it 
should have advantages of some moment in airplane en- 
gines, even though the crank-shaft weight is greater. 



Bail-Bearing Crank- Shafts 319 

BALL-BEARING CRANK-SHAFTS 

While crank-shafts are usually supported in plain 
journals there seems to be a growing tendency of late 
to use anti-friction bearings of the ball type for their 
support. This is especially noticeable on block motors 
where but two main bearings are utilized. When ball 
bearings are selected with proper relation to the load 
which obtains they will give very satisfactory service. 
They permit the crank-shaft to turn with minimum fric- 
tion, and if properly selected will never need adjustment. 
The front end is supported by a bearing which is clamped 
in such a manner that it will take a certain amount of 
load in a direction parallel to the axis of the shaft, while 
the rear end is so supported that the outer race of the 
bearing has a certain amount of axial freedom or " float.' ' 
The inner race or cone of each bearing is firmly clamped 
against shoulders on the crank- shaft. At the front end 
of the crank-shaft timing gear and a suitable check nut 
are used, while at the back end the bearing is clamped 
by a threaded retention member between the fly-wheel 
and a shoulder on the crank-shaft. The fly-wheel is held 
in place by a, taper and key retention. The ball bearings 
are carried in a light housing of bronze or malleable iron, 
which in turn are held in the crank-case by bolts. The 
Eenault engine uses ball bearings at front and rear ends 
of the crank-shaft, but has plain bearings around inter- 
mediate crank-shaft journals. The rotary engines of the 
Gnome, Le Rhone and Clerget forms would not be prac- 
tical if ball bearings were not used as the bearing fric- 
tion and consequent depreciation would be very high. 

ENGINE-BASE CONSTRUCTION 

One of the important parts of the power plant is the 
substantial casing or bed member, which is employed to 
support the cylinders and crank-shaft and which is at- 
tached directly to the fuselage engine supporting mem- 



320 



Aviation Engines 



bers. This will vary widely in form, but as a general 
thing it is an approximately cylindrical member which 
may be divided either vertically or horizontally in two 
or more parts. Airplane engine crank-cases are usually 
made of aluminum, a material which has about the same 
strength as cast iron, but which only weighs a third as 
much. In rare cases cast iron is employed, but is not 
favored by most engineers because of its brittle nature, 




Fig. 140. — View of Thomas 135 Horse-Power Aeromotor, Model 8, Showing" 
Conventional Method of Crank-Case Construction. 



great weight and low resistance to tensile stresses. Where 
exceptional strength is needed alloys of bronze may be 
used, and in some cases where engines are produced in 
large quantities a portion of the crank-case may be a 
sheet steel or aluminum stamping. 

Crank-cases are always large enough to permit the 
crank-shaft and parts attached to it to turn inside and 
obviously its length is determined by the number of cylin- 
ders and their disposition. The crank-case of the radial 
cylinder or double-opposed cylinder engine would be sub- 
stantially the same in length. That of a four-cylinder 



Crank-Case Construction 321 

will vary in length with the method of casting the cylin- 
der. When the four-cylinders are cast in one unit and 
a two-bearing crank-shaft is used, the crank-case is a very 




Fig. 141. — Views of Upper Half of Thomas Aeromotor Crank-Case. 

compact and short member. When a three-bearing crank- 
shaft is utilized and the cylinders are cast in pairs, the 
engine base is longer than it would be to support a block 
casting, but is shorter than one designed to sustain in- 



322 



Aviation Engines 



dividual cylinder castings and a five-bearing crank-shaft. 
It is now common construction to cast an oil container 
integral with the bottom of the engine base and to draw 
the lubricating oil from it by means of a pump, as shown 
at Fig. 140. The arms by which the motor is supported 



Exhaust Ports-* 



Inlet Ports 
Exhaust Ports . 




Right Hand Cylinder Block 
Note: Rigidity and cleanliness of design 
also ceniral inlet port locations 
for even distribution of gas 



Exhaust Ports ,..., 



Inlet Ports 
Exhaust Ports - -\ 




Oil Duct to Cam Shaft 

\ Bearing and Front 

Gear Case 



Crank Shaft Bearing 
Oil Ports 



'Oil Return No + e . Bearing Supports 

Left Hand Cylinder Block Casting 



Fig. 142. — Method of Constructing Eight-Cylinder Vee Engine, Possible 
if Aluminum Cylinder and Crank-Case Castings are Used. 



Crank-Case Construction 



323 



in the fuselage are substantial-ribbed members cast inte- 
grally with the upper half. 

The approved method of crank-case construction fa- 
vored by the majority of engineers is shown at the top of 
Fig. 141, bottom side up. The upper half not only forms 
a bed for the cylinder but is used to hold the crank-shaft 
as well. In the illustration, the three-bearing boxes form 
part of the case, while the lower brasses are in the form 



1 




p 


- r - /r: : %J^ 


' 



Fig. 143. — Simple and Compact Crank-Case, Possible When Radial Cylinder 
Engine Design is Followed. 

of separately cast caps retained by suitable bolts. In 
the construction outlined the bottom part of the case 
serves merely as an oil container and a protection for 
the interior mechanism of the motor. The cylinders are 
held down by means of studs screwed into the crank-case 
top, as shown at Fig. 141, lower view. If the aluminum 
cylinder motor has any future, the method of construc- 
tion outlined at Fig. 142, which has been used in cast iron 
for an automobile motor, might be used for an eight- 
cylinder Vee engine for airplane use. The simplicity of 
the crank-case needed for a revolving cylinder motor 
and its small weight can be well understood by examina- 
tion of the illustration at Fig. 143, which shows the en- 
gine crank-case for the nine-cylinder "Monosoupape" 
Gnome engine. This consists of two accurately machined 
forgings held together by bolts as clearly indicated. 



CHAPTER X 

Power Plant Installation — Curtiss OX 2 Engine Mounting and Operating 
Rules — Standard S. A. E. Engine Bed Dimensions — Hall-Scott 
Engine Installation and Operation — Fuel System Rules — Ignition 
System — Water System — Preparations to Start Engine — Mounting 
Radial and Rotary Engines — Practical Hints to Locate Engine 
Troubles — All Engine Troubles Summarized — Location of Engine 
Troubles Made Easy. 

The proper installation of the airplane power plant 
is more important than is generally supposed, as while 
these engines are usually well balanced and run with little 
vibration, it is necessary that they be securely anchored 
and that various connections to the auxiliary parts Be 
carefully made in order to prevent breakage from vibra- 
tion and that attendant risk of motor stoppage while in 
the air. The type of motor to be installed determines 
the method of installation to be followed. As a general 
rule six-cylinder vertical engine and eight-cylinder Vee 
type are mounted in substantially the same way. The 
radial, fixed cylinder forms and the radial, rotary cylin- 
der Gnome and Ehone rotary types require an entirely 
different method of mounting. Some unconventional 
mountings have been devised, notably that shown at Fig. 
144, which is a six-cylinder German engine that is in- 
stalled in just the opposite way to that commonly fol- 
lowed. The inverted cylinder construction is not gen- 
erally followed because even with pressure feed, dry 
crank-case type lubricating system there is considerable 
danger of over-lubrication and of oil collecting and car- 
bonizing in the combustion chamber and gumming up 
the valve action much quicker than would be the case if 
the engine was operated in the conventional upright posi- 
tion. The reason for. mounting an engine in this way is 
to obtain a lower center of gravity and also to make for 

324 






Power Plant Installation 



325 



more perfect streamlining of the front end of the fuselage 
in some cases. It is rather doubtful if this slight ad- 
vantage will compensate for the disadvantages intro- 
duced by this unusual construction. It is not used to 
any extent now but is presented merely to show one of 
the possible systems of installing an airplane engine. 

In a number of airplanes of the tractor-biplane type 
the power plant installation is not very much different 




Fig. 144. — Unconventional Mounting of German Inverted Cylinder Motor. 



than that which is found in automobile practice. The 
illustration at Fig. 145 is a very clear representation of 
the method of mounting the Curtiss eight-cylinder 90 
H. P. or model 0X2 engine in the fuselage of the Curtiss 
JN4 tractor biplane which is so generally used in the 
United States as a training machine. It will be observed 
that the fuel tank is mounted under a cowl directly behind 
the motor and that it feeds the carburetor by means of a 



326 



Aviation Engines 



flexible fuel pipe. As the tank is mounted higher than the 
carburetor, it will feed that member by gravity. The 
radiator is mounted at the front end of the fuselage and 
connected to the water piping on the motor by the usual 
rubber hose connections. An oil pan is placed under the 
engine and the top is covered with a hood just as in 
motor car practice. The panels of aluminum are attached 




Fig. 145. — How Curtiss Model 0X2 Motor is Installed in Fuselage of 
Curtiss Tractor Biplane. Note Similarity of Mounting to Automobile 
Power Plant. 



to the sides of the fuselage and are supplied with doors 
which open and provide access to the carburetor, oil- 
gauge and other parts of the motor requiring inspection. 
The complete installation with the power plant enclosed 
is given at Fig. 146, and in this it will be observed that 
the exhaust pipes are connected to discharge members 
that lead the gases above the top plane. In the engine 
shown at Fig. 145 the exhaust flows directly into the air 
at the sides of the machine through short pipes bolted to 
the exhaust gas outlet ports. The installation of the 




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327 



328 



Aviation Engines 



radiator just back of the tractor screw insures that ade- 
quate cooling will be obtained becanse of the rapid air 
flow due to the propeller slip stream. 

INSTALLATION OF CURTISS 0X2 ENGINE 

The following instructions are given in the Curtiss 
Instruction Book for installing the 0X2 engine and pre- 
paring it for flights, and taken in connection with the very 



•Flexible Exhaust Discharge Pipes 

, r Exhaust Manifolds 

Radiator, 







Propeller)] 

iiii I Shaft \ 

End J 



■ V W4\ K 



Fig. 147. — Front View of L. W. F. Tractor Biplane Fuselage, Showing 
Method of Installing Thomas Aeromotor and Method of Disposing of 
Exhaust Gases. 



clear illustration presented no difficulty should be experi- 
enced in understanding the proper installation, and mount- 
ing of this power plant. The bearers or beds should be 
2 inches wide by 3 inches deep, preferably of laminated 
hard wood, and placed 11% inches apart. They must be 
well braced. The six arms of the base of the motor are 



Curtis OX2 Engine Installation 329 

drilled for %-inch bolts, and none but this size should 
be used. 

1. Anchoring the Motor. Put the bolts in from the 
bottom, with a large washer under the head of each so 
the head cannot cut into the wood. On every bolt use a 
castellated nut and a cotter pin, or an ordinary nut and 
a lock washer, so the bolt will not work loose. Always 
set motor in place and fasten before attaching any aux- 
iliary apparatus, such as carburetor, etc. 

2. Inspecting the Ignition-Sivitch Wires. The wires 
leading from the ignition switch must be properly con- 
nected — one end to the motor body for ground, and the 
other end to the post on the breaker box of the magneto. 

3. Filling the Radiator. Be sure that the water from 
the radiator fills the cylinder jackets. Pockets of air 
may remain in the cylinder jackets even though the 
radiator may appear full. Turn the motor over a few 
times by hand after filling the radiator, and then add 
more water if the radiator will take it. The air pockets, 
if allowed to remain, may cause overheating and develop 
serious trouble when the motor is running. 

4. Filling the Oil Reservoir. Oil is admitted into the 
crank-case through the breather tube at the rear. It is 
well to strain all oil put into the crank-case. In filling the 
oil reservoir be sure to turn the handle on the oil sight- 
gauge till it is at right angles with the gauge. The oil 
sight-gauge is on the side of the lower half of the crank- 
case. Put in about 3 gallons of the best obtainable oil, 
Mobile B recommended. It is important to remember 
that the very best oil is none too good. 

5. Oiling Exposed Moving Parts. Oil all rocker-arm 
bearings before each flight. A little oil should be applied 
where the push rods pass through the stirrup straps. 

6. Filling the Gasoline Tanks. Be certain that all 
connections in the gasoline system are tight. 

7. Turning on the Gasoline. Open the cock leading 
from the gasoline tank to the carburetor. 

8. Charging the Cylinders. With the ignition switch 



330 Aviation Engines 

OFF, prime the motor by squirting a little gasoline in 
each exhanst port and then turn the propeller backward 
two revolutions. Never open the exhaust valve by oper- 
ating the rocker-arm by hand, as the push-rod is liable to 
come out of its socket in the cam follower and bend the 
rocker-arm when the motor turns over. 

9. Starting the Motor by Hand. Always retard the 
spark part way, to prevent back-firing, by pulling for- 
ward the wire attached to the breaker box. Failure to so 
retard the spark in starting may result in serious injury 
to the operator. Turn on the ignition switch with throttle 
partly open; give a quick, strong pull down and outward 
on the starting crank or propeller. As soon as the motor 
is started advance the spark by releasing the retard wire. 

10. Oil Circulation. Let the motor run at low speed 
for a few minutes in order to establish oil circulation in 
all bearings. With all parts functioning properly, the 
throttle may be opened gradually for warming up before 
flight. 

STANDARD S.A.E. ENGINE BED DIMENSIONS 

The Society of Automotive Engineers have made ef- 
forts to standardize dimensions of bed timbers for sup- 
porting power plant in an aeroplane. Owing to the great 
difference in length no standardization is thought possible 
in this regard. The dimensions recommended are as 
follows : 

Distance between timbers 12 in. 14 in. 16 in. 

Width of bed timbers 1 % in. 1 % in. 2 in. 

Distance between centers of bolts. 13^ in. 15% in. 18 in. 

It will be evident that if any standard of this nature 
were adopted by engine builders that the designers of 
fuselage could easily arrange their bed timbers to con- 
form to these dimensions, whereas it would be difficult to 
have them adhere to any standard longitudinal dimen- 
sions which are much more easily varied in fuselages 
than the transverse dimensions are. It, however, should 



Standard Engine Bed Dimensions 



331 




- 7-—-X 



i /SC/Tr/7t /7a/rr/rr i I 

(< s" ->)<--- a* -J 



I 



94 -- 



•I 



- 9i'-- 

Z3S/r7S77 



332 



Aviation Engines 



be possible to standardize the longitudinal positions of 
the holding down bolts as the engine designer wonld still 
be able to allow himself considerable space fore-and-aft 
of the bolts. 

HALL-SCOTT ENGINE INSTALLATION 

The very thorough manner in which installation dia- 
grams are prepared by the leading engine makers leaves 
nothing to the imagination. The dimensions of the Hall- 
Scott four-cylinder airplane engine are given clearly in 




Fig. 149.— Plan and Side Elevation of Hall-Scott A-7 Four-Cylinder Air- 
plane Engine, -with Installation Dimensions. 



Engine Installation 333 

our inch measurements with the metric equivalents at 
Figs. 148 and 149, the former showing a vertical eleva- 
tion while the latter has a plan view and side elevation. 
The installation of this engine in airplanes is clearly 
shown at Figs. 150 and 151, the former having the radi- 
ator installed at the front of the motor and having all 
exhaust pipes joined to one common discharge funnel, 



Fig. 150. 

CENSORED 



which deflects the gas over the top plane while the latter 
has the radiator placed vertically above the motor at 
the back end and has a direct exhaust gas discharge to 
the air. 

The dimensions of the six-cylinder Hall-Scott motor 
which is known as the type A-5 125 H. P. are given at 
Fig. 152, which is an end sectional elevation, and at Fig. 
153, which is a plan view. The dimensions are given both 
in inch sizes and the metric equivalents. The appearance 






334 Aviation Engines 

of a Hall-Scott six-cylinder engine installed in a fuselage 
is given at Fig. 154, while a diagram showing the loca- 
tion of the engine and the various pipes leading to the 
auxiliary groups is outlined at Fig. 155. The following 
instructions for installing the Hall-Scott power plant are 



Fig. 151. 

CENSORED 



Engine Installation 335 



Fig. 152. 

CENSORED 



336 



Aviation Engines 



reproduced from the instruction book issued by the maker. 
Operating instructions which are given should enable any- 
good mechanic to make a proper installation and to keep 
the engine in good running condition. 



FUEL SYSTEM INSTALLATION 



Gasoline giving the best results with this equipment 
is as follows: Gravity 58-62 deg. Baume A. Initial boil- 
ing point — Kichmond method — 102° Fahr. Sulphur .014. 



yes mm. 

w 


y 


I6SHH 

V 


y 


I6SMM. 

Bl5 




7%* 

i ei mm. 



Fig. 153.— Plan View of Hall-Scott Type A-5 125 Horse-Power Airplane 
Engine, Showing Installation Dimensions. 

Calorimetric bomb test 20610 B. T. U. per pound. If the 
gasoline tank is placed in the fuselage below the level of 
the carburetor, a hand pump must be used to maintain 
air pressure in gas tank to force the gasoline to the car- 
buretor. After starting the engine the small auxiliary air 
pump upon the engine will maintain sufficient pressure. 
A-7a and A-5a engines are furnished with a new type 
auxiliary air pump. This should be frequently oiled and 
care taken so no grit or sand will enter which might lodge 
between the valve and its seat, which would make it fail 
to operate properly. An air relief valve is furnished with 
each engine. It should be screwed into the gas tank and 
properly regulated to maintain the pressure required. 



Hall-Scott Engine Installation 



337 



This is done by screwing the ratchet on top either up or 
down. If two tanks are nsed in a plane one should be 
installed in each tank. All air pump lines should be care- 




Fig. 154. — Three-Quarter View of Hall-Scott Type A-5 125 Horse-Power 
Six-Cylinder Engine, with One of the Side Radiators Removed to 
Show Installation in Standard Fuselage. 




338 



Engine Installation 339 

fully gone over quite frequently to ascertain if they are 
tight. Check values have to be placed in these lines. In 
some cases the gasoline tank is placed above the engine, 
allowing it to drain by gravity to the carburetor. When 
using this system there should be a drop of not less than 
two feet from the lowest portion of the gasoline tank to 
the upper part of the carburetor float chamber. Even 
this height might not be sufficient to maintain the proper 
volume of gasoline to the carburetor at high speeds. Air 
pressure is advised upon all tanks to insure the proper 
supply of gasoline. When using gravity feed without 
air pressure be sure to vent the tank to allow circulation 
of air. If gravity tank is used and the engine runs satis- 
factorily at low speeds but cuts out at high speeds the 
trouble is undoubtedly due to insufficient height of the 
tank above the carburetor. The tank should be raised or 
air pressure system used. 

IG^ITIO^" SWITCHES 

Two " DIXIE" switches are furnished with each en- 
gine. Both of these should be installed in the pilot's 
seat, one controlling the E. H., and the other the L. H. 
magneto. By shorting either one or the other it can be 
quickly determined if both magnetos, with their respec- 
tive spark-plugs, are working correctly. Care should be 
taken not to use spark-plugs having special extensions or 
long 'protruding points. Plugs giving best results are ex- 
tremely small with short points. 

WATER SYSTEMS 

A temperature gauge should be installed in the water 
pipe, coming directly from the cylinder nearest the pro- 
peller (note illustration above). This instrument in- 
stalled in the radiator cap has not always given satis- 
factory results. This is especially noticeable when the 
water in the radiator becomes low, not allowing it to 
touch the bulb on the moto-meter. For ordinary running, 



340 Aviation Engines 

it should not indicate over 150 degrees Fahr. In climb- 
ing tests, however, a temperature of 160 degrees Fahr. 
can be maintained without any ill effects upon the en- 
gine. In case the engine becomes overheated, the indi- 
cator will register above 180 degrees Fahr., in which case 
it should be stopped immediately. Overheating is most 
generally caused by retarded spark, excessive carbon in 
the cylinders, insufficient lubrication, improperly timed 
valves, lack of water, clogging of water system in any 
way which would obstruct the free circulation of the 
water. 

Overheating will cause the engine to knock, with pos- 
sible damaging results. Suction pipes should be made 
out of thin tubing, and run within a quarter or an eighth 
of an inch of each other, so that when a hose is placed 
over the two, it will not be possible to suck together. 
This is often the case when a long rubber hose is used, 
which causes overheating. Eadiators should be flushed 
out and cleaned thoroughly quite often. A dirty radiator 
may cause overheating. 

When filling the radiator it is very important to re- 
move the plug on top of the water pump until water 
appears. This is to avoid air pockets being formed in the 
circulating system, which might not only heat up the 
engine, but cause considerable damage. All water pump 
hoses and connections should be tightly taped and shel- 
lacked after the engine is properly installed in the plane. 
The greatest care should be taken when making engine 
installation not to use smaller inside diameter hose con- 
nection than water pump suction end casting. One inch 
and a quarter inside diameter should be used on A-7 and 
A-5 motors, while nothing less than one inch and a half 
inside diameter hose or tubing on all A-7a and A-5a en- 
gines. It is further important to have light spun tubing, 
void of any sharp turns, leads from pump to radiator and 
cylinder water outlet to radiator. In other words, the 
water circulation through the engine must be as little 
restricted as possible. Be sure no light hose is used, that 



Preparations to Start Engine 341 

will often suck together when engine is started. To thor- 
oughly drain the water from the entire system, open the 
drain cock at the lowest side of the water pump. 

PREPARATIONS TO START ENGINE 

Always replenish gasoline tanks through a strainer 
which is clean. This strainer must catch all water and 
other impurities in the gasoline. Pour at least three 
gallons of fresh oil into the lower crank-case. Oil all 
rocker arms through oilers upon rocker arm housing caps. 
Be sure radiators are filled within one inch of the top. 

After all the parts are oiled, and the tanks filled, the 
following must be looked after before starting: See if 
crank-shaft flange is tight on shaft. See if propeller bolts 
are tight and evenly drawn up. See if propeller bolts are 
wired. See if propeller is trued up to within %". 

Every four days the magnetos should be oiled if the 
engine is in daily use. 

Every month all cylinder hold-down nuts should be 
gone over to ascertain if they are tight. (Be sure to re- 
cotter nuts.) 

See if magnetos are bolted on tight and wired. 

See if magneto cables are in good condition. 

See if rocker arm tappets have a .020" clearance from 
valve stem when valve is seated. 

See if tappet clamp screws are tight and cottered. 

See if all gasoline, oil, water pipes and connections are 
in perfect condition. 

Air on gas line should be tested for leaks. 

Pump at least three pounds air pressure into gasoline 
tank. 

After making sure that above rules have been ob- 
served, test compression of cylinders by turning propeller. 

"do not forget to short both magnetos" 

Be sure all compression release and priming cocks do 
not leak compression. If they do, replace same with a 



342 Aviation Engines 

new one immediately, as this might cause premature 
firing. 

Open priming cocks and squirt some gasoline into each. 

Close cocks. 

Open compression release cocks. 

Open throttle slightly. 

If using Berling magnetos they should be three-quar- 
ters advanced. 

If all the foregoing directions have been carefully 
followed, the engine is ready for starting. 

In cranking engine either by starting crank, or pro- 
peller, it is essential to throw it over compression quickly. 

Immediately upon starting, close compression release 
cocks. 

When engine is running, advance magnetos. 

After it has warmed up, short one magneto and then 
the other, to be sure both magnetos and spark-plugs are 
firing properly. If there is a miss, the fouled plug must 
be located and cleaned. There is a possibility that the 
jets in the carburetor are stopped up. If this is the case, 
do not attempt to clean same with any sharp instrument. 
If this is done, it might change the opening in the jets, 
thus spoiling the adjustment. Jets and nozzles should 
be blown out with air or steam. 

An open intake or exhaust valve, which might have 
become sluggish or stuck from carbon, might cause 
trouble. Be sure to remedy this at once by using a little 
coal-oil or kerosene on same, working the valve by hand 
until it becomes free. We recommend using graphite on 
valve stems mixed with oil to guard against sticking or 
undue wear. 

INSTALLING ROTARY AND RADIAL CYLINDER ENGINES 

When rotary engines are installed simple steel stamp- 
ing or "spiders" are attached to the fuselage to hold the 
fixed crank-shaft. Inasmuch as the motor projects clear 
of the fuselage proper there is plenty of room back of 



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313 



344 



Aviation Engines 



the front spider plate to install the auxiliary parts such 
as the oil pump, air pump and ignition magneto and also 
the fuel and oil containers. The diagram given at Fig. 
156 shows how a Gnome "monosoupape" engine is in- 
stalled on the anchorage plates and it also outlines clearly 
the piping necessary to convey the oil and fuel and also 
the air-piping needed to put pressure on both fuel and 
oil tanks to insure positive supply of these liquids which 



<—-Air Screw 




Motor in 
Front 



Tractor Screw--*' 
in Front 




VAl— ± 



Motor in Rear 



Fig. 157. — Showing Two Methods of Placing Propeller on Gnome Rotary- 
Motor. 



may be carried in tanks placed lower than the motor in 
some installations. The diagram given at Figs. 157 and 
158 shows other mountings of Gnome engines and are 
self-explanatory. The simple mounting possible when the 
Anzani ten-cylinder radial fixed type engine is used given 
at Fig. 159. The front end of the fuselage is provided 
with a substantial pressed steel plate having members 
projecting from it which may be bolted to the longer- 
ons. The bolts that hold the two halves of the crank- 
case together project through the steel plate and hold the 
engine securely to the front end of the fuselage. 



Location of Engine Troubles 



345 



PRACTICAL. HIXTS TO LOCATE EXGLXE TROUBLES 

One who is not thoroughly familiar with engine con- 
struction will seldom locate troubles by haphazard experi- 
menting and it is only by a systematic search that the 
cause can be discovered and the defects eliminated. In 
this chapter the writer proposes to outline some of the 
most common power-plant troubles and to give sufficient 



K 



Fr f Roiary .-Upper 

Engine Mofor '; / Longeron 

Support 



J ' ^V' I £---■ Rear Engine Support 



'Carburetor 



.Upper 

\ Longerons -.„ 



Front Engine 
Support 





'"•Tractor Screw 

S ide View 



Lower 
Longeron 



■Lower Longerons-''' 
Front View 



Fig. 158. — How Gnome Rotary Motor May Be Attached to Airplane 

Fuselage Members. 



advice to enable those who are not thoroughly informed 
to locate them by a logical process of elimination. The 
internal-combustion motor, which is the power plant of 
all gasoline automobiles as well as airplanes, is composed 
of a number of distinct groups, which in turn include dis- 
tinct components. These various appliances are so closely 
related to each other that defective action of any one may 
interrupt the operation of the entire power plant. Some 
of the auxiliary groups are more necessary than others 
and the power plant will continue to operate for a time 
even after the failure of some important parts of some 
of the auxiliary groups. The gasoline engine in itself is 



346 



Aviation Engines 



a complete mechanism, but it is evident that it cannot 
deliver any power without some means of supplying gas 
to the cylinders and igniting the compressed gas charge 
after it has been compressed in the cylinders. From this 



Fixed Cylinder 
Radial Engine 




Engine 
Supporting 
Plate 



landing 
Gear Struts 



A.G. HA GST BOM NY. 



Fig. 159.— How Anzani Ten-Cylinder Radial Engine is Installed to Plate 
Securely Attached to Front End of Tractor Airplane Fuselage. 



Typical Engine Stoppage Analyzed 347 

it is patent that the ignition and carburetion systems are 
just as essential parts of the power plant as the piston, 
connecting rod, or cylinder of the motor. The failure of 
either the carburetor or igniting means to function prop- 
erly Trill be immediately apparent by faulty action of the 
power plant, 

To insure that the motor Trill continue to operate it 
is necessary to keep it from overheating by some form of 
cooling system and to supply oil to the moving parts to 
reduce friction. The cooling and lubrication groups are 
not so important as carburetion and ignition, as the en- 
gine would run for a limited period of time even should 
the cooling system fail or the oil supply cease. It would 
only be a few moments, however, before the engine would 
overheat if the cooling system was at fault, and the parts 
seize if the lubricating system should fail. Any derange- 
ment in the carburetor or ignition mechanism would man- 
ifest itself at once because the engine operation would be 
affected, but a defect in the cooling or oiling system would 
not be noticed so readily. 

The careful aviator will always inspect the motor 
mechanism before starting on a trip of any consequence, 
and if inspection is carefully carried out and loose parts 
tightened it is seldom that irregular operation will be 
found due to actual breakage of any of the components 
of the mechanism. Deterioration due to natural causes 
matures slowly, and sufficient warning is always given 
when parts begin to wear so satisfactory repairs may be 
promptly made before serious derangement or failure is 
manifested. 



A TYPICAL EXGIXE STOPPAGE ANALYZED 

Before describing the points that may fail in the vari- 
ous auxiliary systems it will be well to assume a typical 
case of engine failure and show the process of locating 
the trouble in a systematic manner by indicating the 
various steps which are in logical order and which could 



348 



Aviation Engines 



reasonably be followed. In any case of engine failure the 
ignition system, motor compression, and carburetor should 
be tested first. If the ignition system is functioning prop- 
erly one should determine the amount of compression in 
all cylinders and if this is satisfactory the carbureting 
group should be tested. If the ignition system is working 
properly and there is a decided resistance in the cylinders 




Fig. 160. — Side Elevation of Thomas 135 Horse-Power Airplane Engine, 
Giving Important Dimensions. 

when the propeller is turned, proving that there is good 
compression, one may suspect the carburetor. 

If the carburetor appears to be in good condition, the 
trouble may be caused by the ignition being out of time, 
which condition is possible when the magneto timing gear 
or coupling is attached to the armature shaft by a taper 
and nut retention instead of the more positive key or 
taper-pin fastening. It is possible that the inlet manifold 
may be broken or perforated, that the exhaust valve is 
stuck on its seat because of a broken or bent stem, broken 
or loose cam, or failure of the cam-shaft drive because 
the teeth are stripped from the engine shaft or cam-shaft 



Engine Troubles Summarized 



349 



gears; or because the key or other fastening on either 
gear has failed, allowing that member to turn independ- 
ently of the shaft to which it normally is attached. The 
gasoline feed pipe may be clogged or broken, the fuel 




Fig. 161. — Front Elevation of Thomas-Morse 135 Horse-Power Aeromotor, 
Showing Main Dimensions. 



supply may be depleted, or the shut-off cock in the gaso- 
line line may have jarred closed. The gasoline filter may 
be filled with dirt or water which prevents passage of the 
fuel. 

The defects outlined above, except the failure of the 



350 Aviation Engines 

gasoline supply, are very rare, and if the container is 
found to contain fuel and the pipe line to be clear to the 
carburetor, it is safe to assume the vaporizing device is 
at fault. If fuel continually runs out of the mixing cham- 
ber the carburetor is said to be flooded. This condition 
results from failure of the shut-off needle to seat properly 
or from a punctured hollow metal float or a gasoline- 
soaked cork float. It is possible that not enough gasoline 
is present in the float chamber. If the passage controlled 
by the float-needle valve is clogged or if the float was 
"badly out of adjustment, this contingency would be prob- 
able. When the carburetor is examined, if the gasoline 
level appears to be at the proper height, one may suspect 
that a particle of lint, or dust, or fine scale, or rust from 
the gasoline tank has clogged the bore of the jet in the 
mixing chamber. 

If the ignition system and carburetor appear to be in 
good working order, and the hand crank shows that there 
is no compression in one or more of the cylinders, it 
means some defect in the valve system. If the engine is 
a multiple-cylinder type and one finds poor compression 
in all of the cylinders it may be due to the rare defect 
of improper valve timing. This may be caused by a gear 
having altered its position on the cam-shaft or crank- 
shaft, because of a sheared key or pin having permitted 
the gear to turn about half of a revolution and then 
having caught and held the gear in place by a broken or 
jagged end so that cam-shaft would turn, but the valves 
open at the wrong time. If but one of the cylinders is 
at fault and the rest appear to have good compression 
the trouble may be due to a defective condition either in- 
side or outside of that cylinder. The external parts may 
be inspected easily, so the following should be looked for: 
9 broken vaf ve, a warped valve-head, broken valve-springs, 
sticking or ben>t valve-stems, dirt under valve-seat, leak 
at valve-chamber cap or spark-plug gasket. Defective 
priming cock, cracked cylinder head (rarely occurs), leak 
through cracked spark - plug insulation, valve - plunger 




s 

pi 



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351 



352 Aviation Engines 

stuck in the guide, lack of clearance between valve-stem 
end and top of plunger caused by loose adjusting screw 
which has worked up and kept the valve from seating. 
The faulty compression may be due to defects inside the 
motor. The piston-head may be cracked (rarely occurs), 
piston rings may be broken, the slots in the piston rings 
may be in line, the rings may have lost their elasticity 
or have become gummed in the groves of the piston, or 
the piston and cylinder walls may be badly scored by a 
loose wrist pin or by defective lubrication. If the motor 
is a type with a separate head it is possible the gasket 
or packing between the cylinder and combustion chamber 
may leak, either admitting water to the cylinder or allow- 
ing compression to escape. 



CONDITIONS THAT CAUSE FAILURE OF IGNITION SYSTEM 

If the first test of the motor had showed that the com- 
pression was as it should be and that there were no seri- 
ous mechanical defects and there was plenty of gasoline 
at the carburetor, this would have demonstrated that the 
ignition system was not functioning properly. If a bat- 
tery is employed to supply current the first step is to take 
the spark-plugs ont of the cylinders and test the system 
by turning over the engine by hand. If there is no spark 
in any of the plugs, this may be considered a positive 
indication that there is a broken main current lead from 
the battery, a defective ground connection, a loose bat- 
tery terminal, or a broken connector. If none of these 
conditions are present, it is safe to say that the battery 
is no longer capable of delivering current. While mag- 
neto ignition is generally used on airplane engines, there 
is apt to be some development of battery ignition, espe- 
cially on engines equipped with electric self-starters which 
are now being experimented with. The spark-plugs may 
be short circuited by cracked insulation or carbon and 
oil deposits around the electrode. The secondary wires 
may be broken or have defective insulation which permits 



Ignition System Failure 353 

the current to ground to some metal part of the fuselage 
or motor. The electrodes of the spark-plug may be too 
far apart to permit a spark to overcome the resistance 
of the compressed gas, even if a spark jumps the air 
space, when the plug is laid on the cylinder. 

If magnetos are fitted as is usually the case at present 
and a spark is obtained between the points of the plug 
and that device or the wire leading to it from the magneto 
is in proper condition, the trouble is probably caused by 
the magneto being out of time. This may result if the 
driving gear is loose on the armature-shaft or crank- 
shaft, and is a rare occurrence. If no spark is produced 
at the plugs the secondary wire may be broken, the ground 
wire may make contact with some metallic portion of the 
chassis before it reaches the switch, the carbon collecting 
brushes may be broken or not making contact, the contact 
points of the make-and-break device may be out of adjust- 
ment, the wiring may be attached to wrong terminals, the 
distributor filled with metallic particles, carbon, dust or 
oil accumulations, the distributor contacts may not be 
making proper connection because of wear and there may 
be a more serious derangement, such as a burned out 
secondary winding or a punctured condenser. 

If the motor runs intermittently, i.e., starts and runs 
only a few revolutions, aside from the conditions pre- 
viously outlined, defective operation may be due to seiz- 
ing between parts because of insufficient oil or deficient 
cooling, too much oil in the crank-case which fouls the 
cylinder after the crank-shaft has revolved a few turns, 
and derangements in the ignition or carburetion systems 
that may be easily remedied. There are a number of 
defective conditions which may exist in the ignition group, 
that will result in " skipping " or irregular operation and 
the following points should be considered first: weak 
source of current due to worn out dry cells or discharged 
storage batteries; weak magnets in magneto, or defective 
contacts at magneto; dirt in magneto distributor or poor 
contact at collecting brushes. Dirty or cracked insulator 



354 Aviation Engines 

at spark-plug will cause short circuit and can only be 
detected by careful examination. The following points 
should also be checked over when the plug is inspected: 
Excessive space betwen electrodes, points too close to- 
gether, loose central electrodes, or loose point on plug 
body, soot or oil particles between electrodes, or on the 
surface of the insulator, cracked insulator, oil or water 
on outside of insulator. Short circuits in the condenser 
or internal wiring of induction coils or magnetos, which 
are fortunately not common, can seldom be remedied ex- 
cept at the factory where these devices were made. If an 
engine stops suddenly and the defect is in the ignition 
system the trouble is usually never more serious than a 
broken or loose wire. This may be easily located by in- 
specting the wiring at the terminals. Irregular operation 
or misfiring is harder to locate because the trouble can 
only be found after the many possible defective conditions 
have been checked over, one by one. 



COMMON" DEFECTS IN FUEL SYSTEMS 

Defective carburetion often causes misfiring or irregu- 
lar operation. The common derangement of the com- 
ponents of the fuel system that are common enough to 
warrant suspicion and the best methods for their location 
follows: First, disconnect the feed pipe from the car- 
buretor and see if the gasoline flows freely from the tank. 
If the stream coming out of the pipe is not the full size 
of the orifice it is an indication that the pipe is clogged 
with dirt or that there is an accumulation of rust, scale, 
or lint in the strainer screens of the filter. It is also 
possible that the fuel shut-off valve may be wholly or 
partly closed. If the gasoline flows by gravity the liquid 
may be air bound in the tank, while if a pressure-feed 
system is utilized the tank may leak so that it does not 
retain pressure; the check valve retaining the pressure 
may be defective or the pipe conveying the air or gas 
under pressure to the tank may be clogged. 



Common Defects in Fuel Systems 355 

If the gasoline flows from the pipe in a steady stream 
the carburetor demands examination. There may be dirt 
or water in the float chamber, which will constrict the 
passage between the float chamber and the spray nozzle, 
or a particle of foreign matter may have entered the 
nozzle and stopped up the fine holes therein. The float 
may bind on its guide, the needle valve regnlating the 
gasoline-inlet opening in bowl may stick to its seat. Any 
of the conditions mentioned would cut down the gasoline 
supply and the engine would not receive sufficient quan- 
tities of gas. The air-valve spring may be weak or the 
air valve broken. The gasoline-adjusting needle may be 
loose and jar out of adjustment, or the air-valve spring- 
adjusting nuts may be such a poor fit on the stem that 
adjustments will not be retained. These instructions ap- 
ply only to carburetors having air valves and mixture 
regulating means which are used only in rare instances 
in airplane work. Air may leak in through the manifold, 
due to a porous casting, or leaky joints in a built up form 
and dilute the mixture. The air-intake dust screen may 
be so clogged with dirt and lint that not enough air will 
pass through the mesh. Water or sediment in the gaso- 
line will cause misfiring because the fuel feed varies when 
the water or dirt constricts the standpipe bore. 

It is possible that the carburetor may be out of ad- 
justment. If clouds of black smoke are emitted at the 
exhaust pipe it is positive indication that too much gaso- 
line is being supplied the mixture and the supply should 
be cut down by screwing in the needle valve on types 
where this method of regulation is provided, and by mak- 
ing sure that the fuel level is at the proper height, or that 
the proper nozzle is used in those forms where the spray 
nozzle has no means of adjustment. If the mixture con- 
tains too much air there will be a pronounced popping 
back in the carburetor. This may be overcome by screw- 
ing in the air-valve adjustment so the spring tension is 
increased or by slightly opening up the gasoline-supply 
regulation needle. When a carburetor is properly ad- 



356 Aviation Engines 

justed and the mixture delivered the cylinder bnrns prop- 
erly, the exhaust gas will be clean and free from the 
objectionable odor present- when gasoline is burned in 
excess. 

The character of combustion may be judged by the 
color of the flame which issues from it when the engine 
is running with an open throttle after nightfall. If the 
flame is red, it indicates too much gasoline. If yellowish, 
it shows an excess of air, while a properly proportioned 
mixture will be evidenced by a pronounced blue flame, 
such as given by a gas-stove burner. 

The Duplex Model 0. D. Zenith carburetor used upon 
most of the six- and eight-cylinder airplane engines con- 
sists of a single float chamber, and a single air intake, 
joined to two separate and distinct spray nozzles, venturi 
and idling adjustments. It is to be noted that as the 
carburetor barrels are arranged side by side, both valves 
are mounted on the same shaft, and work in unison 
through a single operating lever. It is not necessary to 
alter their position. In order to make the engine idle 
well, it is essential that the ignition, especially the spark- 
plugs, should be in good condition. The gaskets between 
carburetor and manifold, and between manifold and cylin- 
ders should be absolutely air-tight. The adjustment for 
low speed on the carburetor is made by turning in or out 
the two knurled screws, placed one on each side of the 
float chamber. After starting the engine and allowing it 
to become thoroughly warmed, one side of the carburetor 
should be adjusted so that the three cylinders it affects 
fire properly at low speed. The other side should be 
adjusted in the same manner until all six cylinders fire 
perfectly at low speed. As the adjustment is changed 
on the knurled screw a difference in the idling of the en- 
gine should be noticed. If the engine begins to run evenly 
or speeds up it shows that the mixture becomes right in 
its proportion. 

Be sure the butterfly throttle is closed as far as pos- 
sible by screwing out the stop screw which regulates the 



Zenith Carburetor Adjustments 357 

closed position for idling. Care shonld be taken to have 
the butterfly held firmly against this stop screw at all 
times while idling engine. If three cylinders seem to run 
irregularly after changing the position of the butterfly, 
still another adjustment may have to be made with the 
knurled screw. Unscrewing this makes the mixture 
leaner. Screwing in closes off some of the air supply to 
the idling jet, making it richer. After one side has been 
made to idle satisfactorily repeat the same procedure with 
the opposite three cylinders. In other words, each side 
should be idled independently to about the same speed. 
Eemember that the main jet and compensating jet 
have no appreciable effect on the idling of the engine. 
The idling mixture is drawn directly through the opening 
determined by the knurled screw and enters the car- 
buretor barrel through the small hole at the edge of each 
butterfly. This is called the priming hole and is only 
effective during idling. Beyond that point the suction is 
transferred to the main jet and compensator, which con- 
trols the power of the engine beyond the idling position 
of the throttle. 

DEFECTS IX OILIXG SYSTEMS 

While troubles existing in the ignition or carburetion 
groups are usually denoted by imperfect operation of 
the motor, such as lost power, and misfiring, derange- 
ments of the lubrication or cooling systems are usually 
evident by overheating, diminution in engine capacity, or 
noisy operation. Overheating may be caused by poor 
carburetion as much as by deficient cooling or insufficient 
oiling. "When the oiling group is not functioning as it 
should the friction between the motor parts produces heat. 
If the cooling system is in proper condition, as will be 
evidenced by the condition of the water in the radiator, 
and the carburetion group appears to be in good condi- 
tion, the overheating is probably caused by some defect 
in the oiling system. 

The conditions that most commonly result in poor 



358 Aviation Engines 

lubrication are: Insufficient oil in the engine crank-case 
or sump, broken or clogged oil pipes, screen at filter filled 
with lint or dirt, broken oil pump, or defective oil-pump 
drive. The supply of oil may be reduced by a defective 
inlet or discharge-check valve at the mechanical oiler or 
worn pumps. A clogged oil passage or pipe leading to 
an important bearing point will cause trouble because 
the oil cannot get between the working surfaces. It is 
well to remember that much of the trouble caused by 
defective oiling may be prevented by using only the best 
grades of lubricant, and even if all parts of the oil sys- 
tem are working properly, oils of poor quality will cause 
friction and overheating. 



DEFECTS m COOLING SYSTEMS OUTLINED 

Cooling systems are very simple and are not liable to 
give trouble as a rule if the radiator is kept full of clean 
water and the circulation is not impeded. "When over- 
heating is due to defective cooling the most common 
troubles are those that impede water circulation. If the 
radiator is clogged or the piping of water jackets filled 
with rust or sediment the speed of water circulation will 
be slow, which will also be the case if the water pump or 
its driving means fail. Any scale or sediment in the water 
jackets or in the piping or radiator passages will reduce 
the heat conductivity of the metal exposed to the air, and 
the water will not be cooled as quickly as though the scale 
was not present. 

The rubber hose often used in making the flexible 
connections demanded between the radiator and water 
manifolds of the engine may deteriorate inside and par- 
ticles of rubber hang down that will reduce the area of 
the passage. The grease from the grease cups mounted 
on the pump-shaft bearing to lubricate that member often 
finds its way into the water system and rots the inner 
walls of the rubber hose, this resulting in strips of the 
partly decomposed rubber lining hanging down and re- 









Cooling System Faults 359 

striding the passage. The cooling system is prone to 
overheat after antifreezing solutions of which calcium 
chloride forms a part have been used. This is due to 
the formation of crystals of salt in the radiator passages 
or water jackets, and these crystals can only be dissolved 
by suitable chemical means, or removed by scraping when 
the construction permits. 

Overheating is often caused by some condition in the 
fuel system that produces too rich or too lean mixture. 
Excess gasoline may be supplied if any of the following 
conditions are present: Bore of spray nozzle or stand- 
pipe too large, auxiliary air-valve spring too tight, gaso- 
line level too high, loose regulating valve, fuel-soaked 
cork float, punctured sheet-metal float, dirt under float 
control shut-off valve or insufficient air supply because 
of a clogged air screen. If pressure feed is utilized there 
may be too much pressure in the tank, or the float con- 
trolled mechanism operating the shut-off in the float bowl 
of the carburetor may not act quickly enough. 

SO^IE CAUSES OF XOISY OPERATION 

There are a number of power-plant derangements 
which give positive indication because of noisy operation. 
Any knocking or rattling sounds are usually produced by 
wear in connecting rods or main bearings of the engine, 
though sometimes a sharp metallic knock, which is very 
much the same as that produced by a loose bearing, is due 
to carbon deposits in the cylinder heads, or premature 
ignition due to advanced spark-time lever. Squeaking 
sounds invariably indicate dry bearings, and whenever 
such a sound is heard it should be immediately located 
and oil applied to the parts thus denoting their dry con- 
dition. Whistling or blowing sounds are produced by 
leaks, either in the engine itself or in the gas manifolds. 
A sharp whistle denotes the escape of gas under pressure 
and is usually caused by a defective packing or gasket 
that seals a portion of the combustion chamber or that is 



360 Aviation Engines 

used for a joint as the exhaust manifold. A blowing 
sound indicates a leaky packing in crank-case. Grinding 
noises in the motor are usually caused by the timing gears 
and will obtain if these gears are dry or if they have be- 
come worn. Whenever a loud knocking sound is heard 
careful inspection should be made to locate the cause of 
the trouble. Much harm may be done in a few minutes 
if the engine is run with loose connecting rod or bearings 
that would be prevented by taking up the wear or loose- 
ness between the parts by some means of adjustment. 

BKIEF SUMMARY OF HINTS FOR STARTING ENGINE 

First make sure that all cylinders have compression. 
To ascertain this, open pet cocks of all cylinders except 
the one to be tested, crank over motor and see that a 
strong opposition to cranking is met with once in two 
revolutions. If motor has no pet cocks, crank and notice 
that oppositions are met at equal distances, two to every 
revolution of the starting crank in a four-cylinder motor. 
If compression is lacking, examine the parts of the cylin- 
der or cylinders at fault in the following order, trying to 
start the motor whenever any one fault is found and 
remedied. See that the valve push rods or rocker arms 
do not touch valve stems for more than approximately 
y 2 revolution in every 2 revolutions, and that there is not 
more than .010 to .020 inch clearance between them de- 
pending on the make of the motor. Make sure that the 
exhaust valve seats. To determine this examine the 
spring and see that it is connected to the valve stem 
properly. Take out valve and see that there is no ob- 
struction, such as carbon, on its seat. See that valve 
works freely in its guide. Examine inlet valve in same 
manner. Listen for hissing sound while cranking motor 
for leaks at other places. 

Make sure that a spark occurs in each cylinder as 
follows: If magneto or magneto and battery with non- 
vibrating coil is used: Disconnect wire from spark-plug, 



Summary of Hints for Starting Engine 361 

hold end about % inch from cylinder or terminal of spark- 
plug. Have motor cranked briskly and see if spark oc- 
curs. Examine adjustment of interrupter points. See that 
wires are placed correctly and not short circuited. Take 
out spark-plug and lay it on the cylinder, being careful 
that base of plug only touches the cylinder and that igni- 
tion wire is connected. Have motor cranked briskly and 
see if spark occurs. Check timing of magneto and see 
that all brushes are making contact. 

See if there is gasoline in the carburetor. See that 
there is gasoline in the tank. Examine valve at tank. 
Prime carburetor and see that spray nozzle passage is 
clear. Be sure throttle is open. Prime cylinders by put- 
ting about a teaspoonful of gasoline in through pet cock 
or spark-plug opening. Adjust carburetor if necessary. 

LOCATION OF EXGIXE TKOUBLES MADE EASY 

The following tabulation has been prepared and origi- 
nated by the writer to outline in a simple manner the 
various troubles and derangements that interfere with 
efficient internal-combustion engine action. The parts 
and their functions are practically the same in all gas or 
gasoline engines of the four-cycle type, and the general 
instructions given apply just as well to all hydro-carbon 
engines, even if the parts differ in form materially. The 
essential components are clearly indicated in the many 
part sectional drawings in this book so they may be 
easily recognized. The various defects that may mate- 
rialize are tabulated in a manner that makes for ready 
reference, and the various defective conditions are found 
opposite the part affected, and under a heading that de- 
notes the main trouble to which the others are con- 
tributing causes. The various symptoms denoting the 
individual troubles outlined are given to facilitate their 
recognition in a positive manner. 

Brief note is also made of the remedies for the restora- 
tion of the defective part or condition. It is apparent 



362 Aviation Engines 

that a table of this character is intended merely as a 
guide, and it is a compilation of practically all the known 
troubles that may materialize in gas-engine operation. 
While most of the defects ontlined are common enongh 
to warrant suspicion, they will never exist in an engine 
all at the same time, and it will be necessary to make a 
systematic search for snch of those as exist. 

To nse the list advantageously, it is necessary to know 
one main trouble easily recognized. For example, if the 
power plant is noisy, look for the possible troubles under 
the head of Noisy Operation; if it lacks capacity, the 
derangement will undoubtedly be found under the head of 
Lost Power. It is assumed in all cases that the trouble 
exists in the power plant or its components, and not in 
the auxiliary members of the ignition, carburetion, lubri- 
cation, or cooling systems. The novice and student will 
readily recognize the parts of the average aviation engine 
by referring to the very complete and clearly lettered 
illustrations of mechanism given in many parts of this 
treatise. 



Lost Power and Overheating 



363 



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Ignition System Troubles 



369 



Ig^itiox System Troubles Oxly 
Motor Will Not Start or Starts Hard 

Loose Battery Terminal. 

Magneto Ground Wire Shorted. 

Magneto Defective (No Spark at Pings). 

Broken Spark Ping Insulation. 

Carbon Deposits or Oil Between Plug Points. 

Spark-Plug Points Too Near Together or Far Apart. 

Wrong Cables to Plugs. 

Short Circuited Secondary Cable. 

Broken Secondary Cable. 



Dry Battery Weak. 
Storage Battery Discharged. 
Poor Contact at Tinier. 
Timer Points Dirty. 



Battery Systems 
Only. ' 



Poor Contact at Switch. 
Primary Wires Broken, or Short Circuited. 
Battery Grounded in Metal Container. 
Battery Connectors Broken or Loose. 
Timer Points Out of Adjustment. 
Defects in Induction Coil. 



Battery and 
Coil Ignition 
System Only. 



Ignition Timing Wrong, Spark Too Late or Too Early. 

Defective Platinum Points in Breaker Box (Magneto). 

Points Not Separating. 

Broken Contact Maker Spring. 

No Contact at Secondary Collector Brush. 

Platinum Contact Points Burnt or Pitted. 

Contact Breaker Bell Crank Stuck. 

Fiber Bushing in Bell Crank Swollen. 

Short Circuiting Spring Always in Contact. 

Dirt or Water in Magneto Casing. 

Oil in Contact Breaker. 

Oil Soaked Brush and Collector Ring. 

Distributor Filled with Carbon Particles. 






370 Aviation Engines 

Motor Stops Without Warning 

Broken Magneto Carbon Brash. 

Broken Lead Wire. 

Broken Ground Wire. 

Battery Ignition Systems. 

Water on High Tension Magneto Terminal. 

Main Secondary Cable Burnt Through by Hot Exhaust 
Pipe (Transformer Coil, Magneto Systems). 

Particle of Carbon Between Spark Ping Points. 

Magneto Short Circuited by Ground Wire. 

Magneto Out of Time, Due to Slipping Drive. 

Water or Oil in Safety Spark Gap (Multi-cylinder Mag- 
neto). 

Magneto Contact Breaker or Timer Stuck in Retard 
Position. 

Worn Fiber Block in Magneto Contact Breaker. 

Binding Fiber Bushing in Contact Breaker Bell Crank. 

Spark Advance Rod or Wire Broken. 

Contact Breaker Parts Stuck. 



Motor Runs Irregularly or Misfires 

Loose Wiring or Terminals. 

Broken Spark-Plug Insulator. 

Spark-Plug Points Sooted or Oily. 

Wrong Spark Gap at Plug Points. 

Leaking Secondary Cable. 

Prematurely Grounded Primary Wire. 

Batteries Running Down (Battery Ignition only). 

Poor Adjustment of Contact Points at Timer. 

Wire Broken Inside of Insulation. 

Loose Platinum Points in Magneto. 

Weak Contact Spring. 

Broken Collector Brush. 

Dirt in Magneto Distributor Casing or Contact Breaker. 

Worn Fiber Block or Cam Plate in Magneto. 



Ignition System Troubles 



371 



"Worn Cam or Contact Koll in Timer (Battery System 

only). 
Dirty Oil in Timer. 
Sticking Coil Vibrators. 
Coil Vibrator Points Pitted. 
Oil Soaked Magneto Winding. 
Punctured Magneto or Coil Winding. 
Distributor Contact Segments Rough. 
Sulphated Storage Battery Terminals. 
Weak Magnets in Magneto. 
Poor Contact at Magneto Contact Breaker Points. 



DEFECTS IN ELECTRICAL SYSTEM COMPONENTS 

To further simplify the location of electrical system 
faults it is thought desirable to outline the defects that 
can be present in the various parts of the individual de- 
vices comprising the ignition system. If an airplane 
engine is provided with magneto ignition solely, as most 
engines are at the present time, no attention need be 
paid to such items as storage or dry batteries, timer or 
induction coil. There seems to be some development in 
the direction of battery ignition so it has been considered 
desirable to include components of these systems as well 
as the almost universally used magneto group. Spark- 
plugs, wiring and switches are needed with either system. 





SPARK-PLUGS 




DEFECT / 


TROUBLE CAUSED 


REMEDY 


Insulation cracked. 


Plug inoperative. 


New insulation. 


Insulation oil soaked. 


Cylinder misfires. 


Clean. 


Carbon deposits. 


Short circuited spark. 


Remove. 


Insulator loose. 


Cylinder misfires. 


Tighten. 


Gasket broken. 


Gas leaks by. 


New gasket. 


Electrode loose on shell. 


Cylinder misfires. 


Tighten. 


Wire loose in insulator. 


Cylinder misfires. 


Tighten. 


Air gap too close. 


Short circuits spark. 


Set correctly. 


Air gap too wide. 


Spark will not jump. 


Set points 1/32" 
apart. 


Loose terminal. 


Cylinder may misfire. 


Tighten. 


Plug loose in cylinder. 


Gas leaks. 


Tighten. 


Mica insulation oil soaked. 


Short circuits spark. 


Replace. 



372 



Aviation Engines 



DEFECT 

Dirty oil in distributor. 
Metal dust in distributor. 
Brushes not making contact. 
Distributor segments worn. 

Collecting brush broken. 

Distributing brush broken. 

Oil soaked winding. 

Magnets loose on pole pieces. 

Armature rubs. 

Bearings worn. 

Magnets weak. 

Contact breaker points pitted. 

Breaker points out of adjust- 
ment 

Defective winding (rare). 

Punctured condenser (rare). 

Driving gear loose. 

Magneto armature out of time. 

Magneto loose on base. 

Contact breaker cam worn. 

Fibre shoe or rolls worn 
(Bosch). 

Fibre bushing binding in con- 
tact lever ( Bosch ; . 

Contact lever return spring 
broken. 

Contact lever return spring 
weak. 

Ground wire grounded. 

Ground wire broken. 

Safety spark gap dirty. 

Fused metal in spark gap. 

Safety spark gap points too 
close. 

Loose distributor terminals. 

Contact breaker sticks. 

Magneto switch short-circuited. 
Magneto switch open circuit. 



MAGNETO 




TROUBLE CAUSED 


EEMEDY 


Engine misfires. 


Clean. 


Engine misfires. 


Clean. 


Current cannot pass. 


Strengthen spring. 


Engine misfires. 


Secure even bear- 


Engine misfires. 


ing. 
New brush. 


Engine misfires. 


New brush. 


Engine misfires. 


Clean. 


Engine misfires. 


Tighten screws. 


Engine misfires. 


Repair bearings. 


Noisy. 


Replace. 


Weak spark. 


Recharge. 


Engine misfires. 


Clean. 


Engine misfires. 


Reset. 


No spark. 


Replace. . 


Weak or no spark. 


Replace. 


Noise. 


Tighten. 


Spark will not fire charge. 


Retime. 


Misfiring and noisy. 


Tighten. 


Misfiring. 


Replace. 


Misfiring. 


Replace. 


Misfiring. 


Ream slightly. 


No spark. 


Replace. 


Misfiring. 


Replace. 


No spark. 


Insulate. 


Engine will not stop. 


Connect up. 


.No spark. 


Clean. 


No spark. 


Remove. 


Misfiring. 


Set properly. 


Misfiring. 


Tighten. 


No spark control. 


Remove and clean 




bearings. 


No spark. 


Insulate. 


No engine stop. 


Restore contact. 



STORAGE BATTERY 



DEFECT 

Electrolyte low. 

Loose terminals. 
Sulphated terminals. 



Battery discharged. 
Electrolyte weak. 

Plates sulphated. 
Sediment or mud in bottom. 
Active material loose in grids. 



TROUBLE CAUSED 

Weak current. 

Misfiring. 
Misfiring. 



Misfiring or no spark. 
Weak current. 

Poor capacity. 
Weak current. 
Poor capacity. 



REMEDY 

Replenish with dis- 
tilled water. 

Tighten. 

Clean thoroughly 
and coat with 
vaseline. 

New charge. 

Bring to proper 
specific gravity. 

Special slow charge. 

Clean out. 

New plates. 



Ignition System Troubles 

STORAGE BATTERY— Continued 



373 



DEFECT 




TKOTJBLE CAUSED 


REMEDY 


Moisture or acid on top 


of 


Shorts terminals. 


Remove. 


cells. 








Plugged vent cap. 




Buckles cell jars. 


Make vent hole. 


Cracked vent cap. 




Acid spills out. 


New cap. 


Cracked cell jar. 




Electrolyte runs out. 


New jar. 




DRY 


CELL BATTERY 




DEFECT 




TROUBLE CAUSED 


REMEDY 


Broken wires. 




No current. 


New wires. 


Loose terminals. 




Misfiring. 


Tighten. 


Weak cell (7 amperes or less). 


Misfiring. 


New cells. 


Cells in contact. 




Short circuit. 


Separate and insu- 
late. 


Water in battery box. 




Short circuit. 
TIMER 


Dry out. 


DEFECT 




TROUBLE CAUSED 


REMEDY 


Contact segments worn 


or 


Misfiring. 


Grind down smooth 


pitted. 








Platinum points pitted. 




Misfiring. 


Smooth with oil 
stone. 


Dirty oil or metal dust 


in 


Misfiring. 


Clean out. 


interior. 








Worn bearing. 




Misfiring. 


Replace. 


Loose terminals. 




Misfiring. 


Tighten. 


Worn revolving contact brush. 


Misfiring. 


Replace. 


Out of time. 




Irregular spark. 


Reset. 



DEFECT 

Loose terminals. 
Broken connections. 
Vibrators out of adjustment. 
Vibrator points pitted. 
Defective condenser \ 
Defective winding ) 
Poor contact at switch. 
Broken internal wiring. 
Poor coil unit. 



INDUCTION COIL 

TROUBLE CAUSED 

Misfiring. 
No spark. 
Misfiring. 
Misfiring. 

No spark. 

Misfiring. ' 

No spark. 

One cylinder affected. 



REMEDY 

Tighten. 

Make new joints. 

Readjust. 

Clean. 

Send to maker for 

repairs. 
Tighten. 
Replace. 
Replace. 



DEFECT 

Loose terminals anywhere. 
Broken plug wire. 
Broken timer wire. 
Broken main battery wire. *) 
Broken battery ground wire. ) 
Broken magneto ground wire. 
Chafed insulation anywhere. ) 
Short circuit anywhere. ) 



WIRING 

TROUBLE CAUSED 

Misfiring. 

One cylinder will not fire. 

One coil will not buzz. 

No spark. 

Engine will not stop. 

Misfiring. 



REMEDY 

Tighten. 
Replace. 
Replace. 

Replace. 

Replace. 

Insulate. 



374 Aviation Engines 

Carburetion System Faults Summarized 
Motor Starts Hard or Will Not Start 

No Gasoline in Tank. 

No Gasoline in Carburetor Float Chamber. 

Tank Shut-Off Closed. 

Clogged Filter Screen. 

Fuel Supply Pipe Clogged. 

Gasoline Level Too Low. 

Gasoline Level Too High (Flooding). 

Bent or Stuck Float Lever. 

Loose or Defective Inlet Manifold. 

Not Enough Gasoline at Jet. 

Cylinders Flooded with Gas. 

Fuel Soaked Cork Float (Causes Flooding ). 

Water in Carburetor Spray Nozzle. 

Dirt in Float Chamber. 

Gas Mixture Too Lean. 

Carburetor Frozen (Winter Only). 

Motor Stops In Flight 

Gasoline Shut-Off Valve Jarred Closed. 

Gasoline Supply Pipe Clogged. 

No Gasoline in Tank. 

Spray Nozzle Stopped Up. 

Water in Spray Nozzle. 

Particles of Carbon Between Spark-Plug Points. 

Magneto Short Circuited by Ground in Wire. 

Air Lock in Gasoline Pipe. 

Broken Air Line or Leaky Tank (Pressure Feed System 

Only). 
Fuel Supply Pipe Partially Clogged. 
Air Vent in Tank Filler Cap Stopped Up (Gravity and 

Vacuum Feed System). 
Float Needle Valve Stuck. 
Water or Dirt in Spray Nozzle. 
Mixture Adjusting Needle Jarred Loose (Eotary Motors 

Only). * 



Carburetion System Faults 375 

Motor Races, Will Not Throttle Doivn 

Air Leak in Inlet Piping. 

Air Leak Through Inlet Valve Guides. 

Control Eods Broken. 

Defective Induction Pipe Joints. 

Leaky Carburetor Flange Packing. 

Throttle Not Closing. 

Poor Slow Speed Adjustment (Zenith Carburetor). 

Motor Misfires 

Carburetor Float Chamber Getting Dry. 

"Water or Dirt in Gasoline. 

Poor Gasoline Adjustment (Rotary Motors). 

Not Enough Gasoline in Float Chamber. 

Too Much Gasoline, Carburetor Flooding. 

Incorrect Jet or Choke (Zenith Carburetor). 

Broken Cylinder Head Packing Between Cylinders. 

Noisy Operation 

Popping or Blowing Back in Carburetor. 

Incorrectly Timed Inlet Valves. 

Inlet Valve Not Seating. 

Defective Inlet Valve Spring. 

Dirt Under Inlet Valve Seat. 

Not Enough Gasoline (Open Needle Valve) . 

Muffler or Manifold Explosions. 

Mixture Not Exploding Regularly. 

Exhaust Valve Sticking. 

Dirt Under Exhaust Valve Seat 



CHAPTER XI 

Tools for Adjusting and Erecting — Forms of Wrenches — Use and Care 
of Files — Split Pin Removal and Installation — Complete Chisel 
Set — Drilling Machines — Drills, Reamers, Taps and Dies — Meas- 
uring Tools — Micrometer Calipers and Their Use — Typical Tool 
Outfits — Special Hall-Scott Tools — Overhauling Airplane Engines 
— Taking Engine Down — Defects in Cylinders — Carbon Deposits, 
Cause and Prevention — Use of Carbon Scrapers — Burning Out 
Carbon with Oxygen — Repairing Scored Cylinders — Valve Re- 
moval and Inspection — Reseating and Truing Valves— Valve 
Grinding Processes — Depreciation in Valve Operating System — 
Piston Troubles — Piston Ring Manipulation — Fitting Piston Rings 
— Wrist-Pin Wear — Inspection and Refitting of Engine Bearings 
— Scraping Brasses to Fit — Fitting Connecting Rods — Testing for 
Bearing Parallelism — Cam-Shafts and Timing Gears — Precautions 
in Reassembling Parts. 

TOOLS FOR ADJUSTING AND ERECTING 

A very complete outfit of small tools, some of which 
are furnished as part of the tool equipment of various 
engines are shown in group at Fig. 163. This group in- 
cludes all of the tools necessary to complete a very prac- 
tical kit and it is not unusual for the mechanic who is 
continually dismantling and erecting engines to possess 
even a larger assortment than indicated. The small bench 
vise provided is a useful auxiliary that can be clamped 
to any convenient bench or table or even fuselage longeron 
in an emergency and should have jaws at least three 
inches wide and capable of opening four or five inches. 
It is especially useful in that it will save trips to the 
bench vises, as it has adequate capacity to handle practi- 
cally any of the small parts that need to be worked on 
when making repairs. A blow torch, tinner's snips and 
soldering copper are very useful in sheet metal work and 
in making any repairs requiring the use of solder. The 
torch can be used in any operation requiring a source of 

376 



AJ3.HAGSTR0W 





Small Bench Vise 
(inner: 



Oil Can 



Piston Ring Remover 

(( 



Hand Vise 



^c 




Small Rivetting I ( }[ 
Hammer n\ iC 

si Machinist's Hammer 



Hacksa' 



r- -> r Q^=e= 



Long Socket Wrench 



Soldering Copper 

n, 



Screw Drivers 
(All Metal Type) 





6||M==^ e ' Side Cutting 

Socket Wrench Set Parallel Jaw Pliers 



Adjustable End Wrench 



Bicycle Wrench I 

Small Socket Wrench Socket 



S+illson Pipe Wrench V> 



ffl 



Goes Monkey Wrench 




End Wrench 

Spark Plug ^-w^y 

Adjustable End Wrench 





) s^?^ 

| Round Nose J ? \\ // [j $&&V-&&ZX& ! te. 
Pliers \ 1} J y .*<r*r- 

'Combina+ion Pliers Cutting |) E^___ 1 

Pliers 



Solid Punch 




Bearing Scraper 



Cold Chisel 

' ...... ■■•■■:■■. /i 

Center Punch 



Files 



<&3* 





Carbon Scrapers End Wrenches Double End Wrenches 



Pig. 163. — Practical Hand Tools Useful in Dismantling and Repairing 

Airplane Engines. 



378 Aviation Engines 

heat. The large box wrench shown under the vise is used 
for removing large special nuts and sometimes has one 
end of the proper size to fit the valve chamber cap. The 
piston ring removers are easily made from thin strips of 
sheet metal securely brazed or soldered to a light wire 
handle. These are used in sets of three for removing 
and applying piston rings in a manner to be indicated. 
The uses of the wrenches, screw drivers, and pliers shown 
are known to all and the variety outlined should be suffi- 
cient for all ordinary work of restoration. The wrench 
equipment is very complete, including a set of open end 
S-wrenches to fit all standard bolts, a spanner wrench, 
socket or box wrenches for bolts that are inaccessible with 
the ordinary type, adjustable end wrenches, a thin monkey 
wrench of medium size, a bicycle wrench for handling 
small nuts and bolts, a Stillson wrench for pipe and a 
large adjustable monkey wrench for the stubborn fasten- 
ings of large size. 

Four different types of pliers are shown, one being a 
parallel jaw type with size cutting attachment, while the 
other illustrated near it is a combination parallel jaw type 
adapted for use on round work as well as in handling 
flat stock. The most popular form of pliers is the com- 
bination pattern shown beneath the socket wrench set. 
This is made of substantial drop forgings having a hinged 
joint that can be set so that a very wide opening at the 
jaws is possible. These can be used on round work and 
for wire cutting as well as for handling flat work. Eound 
nose pliers are very useful also. 

A very complete set of files, including square, half 
round, mill, flat bastard, three-cornered and rat tail are 
also necessary. A hacksaw frame and a number of saws, 
some with fine teeth for tubing and others with coarser 
teeth for bar or solid stock will be found almost indis- 
pensable. A complete punch and chisel set should be pro- 
vided, samples of which are shown in the group while the 
complete outfit is outlined in another illustration. A 
number of different forms and sizes of chisels are neces- 



Forms of Wrenches 379 

sary, as one type is not suitable for all classes of work. 
The adjustable end wrenches can be used in many places 
where a monkey wrench cannot be fitted and where it 
will be difficult to use a wrench having a fixed opening. 
The Stillson pipe wrench is useful in turning studs, round 
rods, and pipes that cannot be turned by any other means. 
A complete shop kit must necessarily include various sizes 
for Stillson and monkey wrenches, as no one size can be 
expected to handle the wide range of work the engine 
repairman must cope with. Three sizes of each form of 
wrench can be used, one, a 6 inch, is as small as is needed 
while a 12 inch tool will handle almost any piece of pipe 
or nut used in engine construction. 

Three or four sizes of hammers should be provided, 
according to individual requirement, these being small 
riveting, medium and heavyweight machinist's hammers. 
A very practical tool of this nature for the repair shop 
can be used as a hammer, screw driver or pry iron. It is 
known as the "Spartan" hammer and is a tool steel drop 
forging in one piece having the working surfaces properly 
hardened and tempered while the metal is distributed so 
as to give a good balance to the head and a comfortable 
grip to the handle. The hammer head provides a posi- 
tive and comfortable T-handle when the tool is used as 
a screw driver or "tommy" bar. Machinist's hammers 
are provided with three types of heads, these being of 
various weights. The form most commonly used is 
termed the "ball pein" on account of the shape of the 
portion used for riveting. The straight pein is just the 
same as the cross pein, except that in the latter the 
straight portion is at right angles to the hammer handle, 
while in the former it is parallel to that member. 

FORMS OF WRENCHES 

Wrenches have been made in infinite variety and there 
are a score or more patterns of different types of ad- 
justable socket and off-set wrenches. The various wrench 



380 



Aviation Engines 



types that differ from the more conventional monkey 
wrenches or those of the Stillson pattern are shown at 
Fig. 164. The "perfect handle" is a drop forged open 
end form provided with a wooden handle similar to that 
nsed on a monkey wrench in order to provide a better 
grip for the hand. The "Saxon" wrench is a double 
alligator form, so called because the jaws are in the form 
of a V-groove having one side of the V plain, while the 
other is serrated in order to secure a tight grip on round 
objects. In the form shown, two jaws of varying sizes 




STARRETT 



Fig. 164. — Wrenches are Offered in Many Forms. 

are provided, one for large work, the other to handle the 
smaller rods. One of the novel features in connection 
with this wrench is the provision of a triple die block in 
the centre of the handle which is provided with three 
most commonly used of the standard threads including 
% 6 -inch-18, %-inch-16, and %-inch-13. This is useful in 
cleaning up burred threads on bolts before they are 
replaced, as burring is unavoidable if it has been neces- 
sary to drive them out with a hammer. The "Lakeside" 
wrench has an adjustable pawl engaging with one of a 
series of notches by which the opening may be held in 
any desired position. 

Ever since the socket wrench was invented it has-been 



Forms of Wrenches 381 

a popular form because it can be used in many places 
where the ordinary open end or monkey wrench cannot 
be applied owing to lack of room for the head of the 
wrench. A typical set which has been made to fit in a very 
small space is shown at D. It consists of a handle, which 
is nickel-plated and highly polished, a long extension bar, 
a universal joint and a number of case hardened cold 
drawn steel sockets to fit all commonly used standard nuts 
and bolt heads. Two screw-driver bits, one small and the 
other large to fit the handle, and a long socket to fit spark- 
plugs are also included in this outfit. The universal joint 
permits one to remove nuts in a position that would be 
inaccessible to any other form of wrench, as it enables 
the socket to be turned even if the handle is at one side 
of an intervening obstruction. 

The "Pick-up" wrench, shown at E, is used for spark- 
plugs and the upper end of the socket is provided with a 
series of grooves into which a suitable blade carried by 
the handle can be dropped. The handle is pivoted to the 
top of the socket in such a way that the blades may be 
picked up out of the grooves by lifting on the end of the 
handle and dropped in again when the handle is swung 
around to the proper point to get another hold on the 
socket. The "Miller" wrench shown at F, is a combina- 
tion socket and open end type, made especially for use 
with spark-plugs. Both the open end and the socket are 
convenient. The "Handy" set shown at G, consists of a 
number of thin stamped wrenches of steel held together 
in a group by a simple clamp fitting, which enables either 
end of any one of the four double wrenches to be brought 
into play according to the size of the nut to be turned. 
The "Cronk" wrench shown at H, is a simple stamping 
having an alligator opening at one end and a stepped 
opening capable of handling four different sizes of stand- 
ard nuts or bolt heads at the other. Such wrenches are 
very cheap and are worth many times their small cost, 
especially for fitting nuts where there is not sufficient 
room to admit the more conventional pattern. The 



382 Aviation Engines 

"Starrett" wrench set, which is shown at I, consists of 
a ratchet handle together with an extension bar and uni- 
versal joint, a spark-plug socket, a drilling attachment 
which takes standard square shank drills from %-inch to 
%-inch in diameter, a double ended screw-driver bit and 
several adjustments to go with the drilling attachment. 
Twenty-eight assorted cold drawn steel sockets similar in 
design to those shown at D, to fit all standard sizes of 
square and hexagonal headed nut's are also included. The 
reversible ratchet handle, which may be slipped over the 
extension bar or the universal joint and which is also 
adapted to take the squared end of any one of the sockets 
is exceptionally useful in permitting, as it does, the in- 
stant release of pressure when it is desired to swing the 
handle back to get another hold on the nut. The socket 
wrench sets are usually supplied in hard wood cases or 
in leather bags so that they may be kept together and 
protected against loss or damage. With a properly se- 
lected socket wrench set, either of the ratchet handle or 
T-handle form, any nut on the engine may be reached and 
end wrenches will not be necessary. 

USE AND CARE OF FILES 

Mention has been previously made of the importance 
of providing a complete set of files and suitable handles. 
These should be in various grades or degrees of fineness 
and three of each kind should be provided. In the flat 
and half round files three grades are necessary, one with 
coarse teeth for roughing, and others with medium and 
fine teeth for the finishing cuts. The round or rat tail 
file is necessary in filing out small holes, the half round 
for finishing the interior of large ones. Half round files 
are also well adapted for finishing surfaces of peculiar 
contour, such as the inside of bearing boxes, connecting 
rod and main bearing caps, etc. Square files are useful 
in finishing keyways or cleaning out burred splines, while 
the triangular section or three-cornered file is of value in 



Use and Care of Files 



383 



cleaning out burred threads and sharp corners. Flat files 
are used on all plane surfaces. 

The file brush shown at Fig. 165, A, consists of a large 
number of wire bristles attached to a substantial wood 



W/tt3KfSTL£S 




Fig. 165. — Illustrating Use and Care of Files. 



back having a handle of convenient form so that the 
bristles may be drawn through the interstices between 
the teeth of the file to remove dirt and grease. If the 



384 Aviation Engines 

teeth are filled with pieces of soft metal, such as solder 
or babbitt, it may be necessary to remove this accumula- 
tion with a piece of sheet metal as indicated at Fig. 
165, B. The method of holding a file for working on 
plain surfaces when it is fitted with the regular form of 
wooden handle is shown at C, while two types of handles 
enabling the mechanic to use the flat file on plain sur- 
faces of such size that the handle type indicated at C, 
could not be used on account of interfering with the sur- 
face finished are shown at D. The method of using a 
file when surfaces are finished by draw filing is shown at 
E. This differs from the usual method of filing and is 
only used when surfaces are to be polished and very little 
metal removed. 



SPLIT PIN REMOVAL AND INSERTION 

One of the most widely used of the locking means to 
prevent nuts or bolts from becoming loose is the simple 
split pin, sometimes called a "cotter pin." These can be 
handled very easily if the special pliers shown at Fig. 
166, A, are used. They have a curved jaw that permits 
of grasping the pin firmly and inserting it in the hole 
ready to receive it. It is not easy to insert these split 
pins by other means because the ends are usually spread 
out and it is hard to enter the pin in the hole. With the 
cotter pin pliers the ends may be brought close together 
and as the plier jaws are small the pin may be easily 
pushed in place. Another use of this plier, also indicated, 
is to bend over the ends of the split pin in order to pre- 
vent it from falling out. To remove these pins a simple 
curved lever, as shown at Fig. 166, B, is used. This has 
one end tapering to a point and is intended to be in- 
serted in the eye of the cotter pin, the purchase offered 
by the handle permitting of ready removal of the pin 
after the ends have been closed by the cotter pin pliers. 



Miscellaneous Small Tools 



385 



COMPLETE CHISEL SET 

A complete chisel set suitable for repair shop use is 
also shown at Fig. 166. The type at C is known as a 
"cape" chisel and has a narrow cutting point and is in- 
tended to chip keyways, remove metal out of corners and 
for all other work where the broad cutting edge chisel, 




Fig. 166. — Outlining Use of Cotter Pin Pliers, Spring Winder, and Showing 
Practical Outfit of Chisels. 

shown at D, cannot be used. The form with the wide 
cutting edge is used in chipping, cutting sheet metal, etc. 
At E, a round nose chisel used in making oil ways is out- 
lined, while a similar tool having a pointed cutting edge 
and often used for the same purpose is shown at F. The 
centre punch depicted at G, is very useful for marking 
parts either for identification or for drilling. In addition 



J 



336 Aviation Engines 

to the chisels shown, a number of solid punches or drifts 
resembling very much that shown at E, except that the 
point is blunt should be provided to drive out taper pins, 
bolts, rivets, and other fastenings of this nature. These 
should be provided in the common sizes. A complete set 
of real value would start at %-inch and increase by incre- 
ments of %2-inch up to %-inch. A simple spring winder 
is shown at Fig. 166, H, this making it possible for the 
repairman to wind coil springs, either on the lathe or in 
the vise. It will handle a number of different sizes of 
wire and can be set to space the coils as desired. 



DRILLING MACHINES 

Drilling machines may be of two kinds, hand or power 
operated. For drilling small holes in metal it is neces- 
sary to run the drill fast, therefore the drill chuck is 
usually driven by gearing in order to produce high drill 
speed without turning the handle too fast. A small hand 
drill is shown at Fig. 167, A. As will be observed, the 
chuck spindle is driven by a small bevel pinion, which in 
turn, is operated by a large bevel gear turned by a crank. 
The gear ratio is such that one turn of the handle will 
turn the chuck five or six revolutions. A drill of this 
design is not suited for drills any larger than one-quarter 
inch. For use with drills ranging from one-eighth to 
three-eighths, or even half -inch the hand drill presses 
shown at C and D are used. These have a pad at the 
upper end by which pressure may be exerted with the 
chest in order to feed the drill into the work, and for 
this reason they are termed "breast drills." The form 
at C has compound gearing, the drill chuck being driven 
by the usual form of bevel pinion in mesh with a larger 
bevel gear at one end of a countershaft. A small helical 
spur pinion at the other end of this countershaft receives 
its motion from a larger gear turned by the hand crank. 
This arrangement of gearing permits of high spindle 
speed without the use of large gears, as would be neces- 



Drilling Machines 



387 



sary if but two were used. The form at D gives two 
speeds, one for use with small drills is obtained by en- 
gaging the lower bevel pinion with the chuck spindle and 



fieyeLfirtW 



Chuck 



.CftAM 
3£Y£L $£Ai? 




Fig. 167. — Forms of Hand Operated Drilling Machines. 

driving it by the large ring gear. The slow speed is ob- 
tained by shifting the clutch so that the top bevel pinion 
drives the drill chuck. As this meshes with a gear but 
slightly larger in diameter, a slow speed of the drill 
chuck is possible. Breast drills are provided with a 



j 



388 Aviation Engines 

handle screwed into the side of the frame, these are used 
to steady the drill press. For drilling extremely large 
holes which are beyond the capacity of the usual form 
of drill press the ratchet form shown at B, may be used 
or the bit brace outlined at E. The drills used with either 
of these have square shanks, whereas those used in the 
drill presses have round shanks. The bit brace is also 
used widely in wood work and the form shown is provided 
with a ratchet by which the bit chuck may be turned 
through only a portion of a revolution in either direction 
if desired. 

DRILLS, REAMERS, TAPS AND DIES 

In addition to the larger machine tools and the simple 
hand tools previously described, an essential item of equip- 
ment of any engine or plane repair shop, even in cases 
where the ordinary machine tools are not provided, is a 
complete outfit of drills, reamers, and threading tools. 
Drills are of two general classes, the flat and the twist 
drills. The flat drill has an angle between cutting edges 
of about 110 degrees and is usually made from special 
steel commercially known as drill rod. 

A flat drill cannot be fed into the work very fast be- 
cause it removes metal by a scraping, rather than a 
cutting process. The twist drill in its simplest form is 
cylindrical throughout the entire length and has spiral 
flutes which are ground off at the end to form the cutting 
lip and which also serve to carry the metal chips out of 
the holes. The simplest form of twist drill used is shown 
at Fig. 168, C, and is known as a " chuck" drill, because 
it must be placed in a suitable chuck to turn it. A twist 
drill removes metal by cutting and it is not necessary to 
use a heavy feed as the drill will tend to feed itself into 
the work. 

Larger drills than %-inch are usually made with a 
tapered shank as shown at Fig. 168, B. At the end of 
the taper a tongue is formed which engages with a suit- 
able opening in the collet, as the piece used to support 



Drills and Reamers 



389 



the drill is called. The object of this tongue is to relieve 
the tapered portion of the drill from the stress of driving 
by frictional contact alone, as this would not turn the 
drill positively and the resulting slippage would wear the 
socket, this depreciation changing the taper and making 
it unfit for other drills. The tongue is usually propor- 
tioned so it is adequate to drive the drill under any con- 




Fig. 168. — Forms of Drills Used in Hand and Power Drilling Machines. 



dition. A small keyway is provided in the collet into which 
a tapering key of flat stock may be driven against the 
end of the tongue to drive the drill from the spindle. A 
standard taper for drill shanks generally accepted by the 
machine trade is known as the Morse and is a taper of 
five-eighths of an inch to the foot, The Brown and Sharp 
form tapers six-tenths of an inch to the foot. Care must 
be taken, therefore, when purchasing drills and collets, 



390 Aviation Engines 

to make sure that the tapers coincide, as no attempt 
should be made to run a Morse taper in a Brown and 
Sharp collet, or vice versa. 

Sometimes cylindrical drills have straight flutes, as 
outlined at Fig. 168, A. Such drills are used with soft 
metals and are of value when the drill is to pass entirely 
through the work. The trouble with a drill with spiral 
flutes is that it will tend to draw itself through as the 
cutting lips break through. This catching of the drill 
may break it or move the work from its position. With 
a straight flute drill the cutting action is practically the 
same as with the flat drill shown at Fig. 168, E and F. 

If a drill is employed in boring holes through close- 
grained, tough metals, as wrought or malleable iron and 
steel, the operation will be facilitated by lubricating the 
drill with plenty of lard oil or a solution of soda and 
water. Either of these materials will effectually remove 
the heat caused by the friction of the metal removed 
against the lips of the drill, and the danger of heating 
the drill to a temperature that will soften it by drawing 
the temper is minimized. In drilling large or deep holes 
it is good practice to apply the lubricating medium di- 
rectly at the drill point. Special drills of the form shown 
at Fig. 62, D, having a spiral oil tube running in a 
suitably formed channel, provides communication between 
the point of the drill and a suitable receiving hole on a 
drilled shank. The oil is supplied by a pump and its 
pressure not only promotes positive circulation and re- 
moval of heat, but also assists in keeping the hole free 
of chips. In drilling steel or wrought iron, lard oil 
applied to the point of the drill will facilitate the drill- 
ing, but this material should never be used with either 
brass or cast iron. 

The sizes to be provided depend upon the nature of 
the work and the amount of money that can be invested 
in drills. It is common practice to provide a set of drills, 
such as shown at Fig. 169, which are carried in a suitable 
metal stand, these being known as number drills on ac- 



Drills and Reamers 



391 



count of conforming to the wire gauge standards. Num- 
ber drills do not usually run higher than 5 Ae inch in 
diameter. Beyond this point drills are usually sold by 
the diameter. A set of chuck drills, ranging from % to 
% inch, advancing by %2 inch, and a set of Morse taper 
shank drills ranging from % to 1*4 inches, by increments 
of Viq inch, will be all that is needed for the most pre- 
tentious repair shop, as it is cheaper to bore holes larger 
than 1% inches with a boring tool than it is to carry a 




Fig. 169. — Useful Set of Number Drills, Showing Stand for Keeping These 
in an Orderly Manner. 



number of large drills in stock that would be used very 
seldom, perhaps not enough to justify their cost. 

In grinding drills, care must be taken to have the 
lips of the same length, so that they will form the same 
angle with the axis. If one lip is longer than the other, 
as shown in the flat drill at Fig. 168, E, the hole will be 
larger than the drill size, and all the work of cutting will 
come upon the longest lip. The drill ends should be sym- 
metrical, as shown at Fig. 168, F. 

It is considered very difficult to drill a hole to an exact 
diameter, but for the most work a variation of a few 
thousandths of an inch is of no great moment. "Where 
accuracy is necessary, holes must be reamed out to the 
required size. In reaming, a hole is drilled about %2 inch 



392 



Aviation Engines 



smaller than is required, and is enlarged with a cutting 
tool known as the reamer. Eeamers are usually of the 
fluted form shown at Fig. 170, A. Tools of this nature 
are not designed to remove considerable amounts of 
metal, but are intended to augment the diameter of the 
drill hole by only a small fraction of an inch. Reamers 




Fig. 170. — Illustrating Standard Forms of Hand and Machine Reamers. 

are tapered slightly at the point in order that they will 
enter the hole easily, but the greater portion of the fluted 
part is straight, all cutting edges being parallel. Hand 
reamers are made in either the straight or taper forms, 
that at A, Fig. 170, being straight, while B has tapering 
flutes. They are intended to be turned by a wrench simi- 
lar to that employed in turning a tap, as shown at Fig. 



Types of Reamers and Use 39d 

172, C. The reamer shown at Fig. 170, C, is a hand 
reamer. The form at D has spiral Antes similar to a 
twist drill, and as it is provided with a taper shank it is 
intended to be tnrned by power through the medium of 
a suitable collet. 

As the solid reamers must become reduced in size 
when sharpened, various forms of inserted blade reamers 
have been designed. One of these is shown at E, and as 
the cutting surfaces become reduced in diameter it is 
possible to replace the worn blades with others of proper 
size. Expanding reamers are of the form shown at F, 
These have a bolt passing through that fits into a taper- 
ing hole in the interior of the split reamer portion of the 
tool. If the hole is to be enlarged a few thousandths of 
an inch, it is possible to draw up on the nut just above 
the squared end of the shank, and by drawing the taper- 
ing wedge farther into the reamer body, the cutting por- 
tion will be expanded and will cut a larger hole. 

Keamers must be very carefully sharpened or there 
will be a tendency toward chattering with a consequent 
production of a rough surface. There are several methods 
of preventing this chattering, one being to separate the 
cutting edges by irregular spaces, while the most common 
method, and that to be preferred on machine reamers, is 
to use spiral flutes, as shown at Fig. 170, D. Special 
taper reamers are made to conform to the various taper 
pin sizes which are sometimes used in holding parts to- 
gether in an engine. A taper of M.6 inch per foot is in- 
tended for holes where a pin, once driven in, is to remain 
in place. "When it is desired that the pin be driven out, 
the taper is made steeper, generally 14 inch per foot, 
which is the standard taper used on taper pins. 

"When threads are to be cut in a small hole, it will be 
apparent that it will be difficult to perform this operation 
economically on a lathe, therefore when internal thread- 
ing is called for, a simple device known as a "tap" is 
used. There are many styles of taps, all conforming to 
different standards. Some are for metric or foreign 



394 



Aviation Engines 



threads, some conform to the American standards, while 
others are used for pipe and tubing. Hand taps are the 
form most used in repair shops, these being outlined at 
Fig. 171, A and B; They are usually sold in sets of three, 
known respectively as taper, plug, and bottoming. The 
taper tap is the one first put into the hole, and is then 
followed by the plug tap which cuts the threads deeper. 




vwwww 




fl 



B 




Fig. 171. — Tools for Thread Cutting. 



If it is imperative that the thread should be full size 
clear to the bottom of the hole, the third tap of the set, 
which is straight-sided, is used. It would be difficult to 
start a bottoming tap into a hole because it would be 
larger in diameter at its point than the hole. The taper 
tap, as shown at A, Fig. 171, has a portion of the cutting 
lands ground away at the point in order that it will enter 
the hole. The manipulation of a tap is not hard, as it 
does not need to be forced into the work, as the thread 



Use of Taps and Dies 395 

"will draw it into the hole as the tap is turned. The 
tapering of a tap is done so that no one thread is called 
upon to remove all of the metal, as for about half way up 
the length of the tap each succeeding thread is cut a 
little larger by the cutting edge until the full thread 
enters the hole. Care must be taken to always enter a 
tap straight in order to have the thread at correct angles 
to the surface. 

In cutting external threads on small rods or on small 
pieces, such as bolts and studs, it is not always economi- 
cal to do this work in the lathe, especially in repair work. 
Dies are used to cut threads on pieces that are to be 
placed in tapped holes that have been threaded by the 
corresponding size of tap. Dies for small work are often 
made solid, as shown at Fig. 171, C, but solid dies are 
usually limited to sizes below y 2 inch. Sometimes the 
solid die is cylindrical in shape, with a slot through 
one side which enables one to obtain a slight degree of 
adjustment by squeezing the slotted portion together. 
Large dies, or the sizes over y 2 inch, are usually made 
in two pieces in order that the halves may be closed up 
or brought nearer together. The advantage of this form 
of die is that either of the two pieces may be easily sharp- 
ened, and as it may be adjusted very easily the thread 
may be cut by easy stages. For example, the die may be 
adjusted to cut large, which will produce a shallow thread 
that will act as an accurate guide when the die is closed 
up and a deeper thread cut. 

A common form of die holder for an adjustable die is 
shown at Fig. 172, A. As will be apparent, it consists 
of a central body portion having guide members to keep 
the die pieces from falling out and levers at each end in 
order to permit the operator to exert sufficient force to 
remove the metal. The method of adjusting the depth of 
thread with a clamp screw when a two-piece die is em- 
ployed is also clearly outlined. The diestock shown at 
B is used for the smaller dies of the one-piece pattern, 
having a slot in order that they may be closed up slightly 



396 



Aviation Engines 



by the clamp screw. The reverse side of the diestock 
shown at B is outlined below it, and the guide pieces, 
which may be easily moved in or out, according to the 
size of the piece to be threaded by means of eccentrically 
disposed semi-circular slots in the adjustment plate, are 



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5 



'M^rSctttst 



Fig. 172. — Showing Holder Designs for One- and Two-Piece Thread Cutting 

Dies. 

shown. These movable guide members have small pins 
let into their surface which engage the slots, and they 
may be moved in or out, as desired, according to the posi- 
tion of the adjusting plate. The use of the guide pieces 
makes for accurate positioning or centering of the rod to 
be threaded. Dies are usually sold in sets, and are com- 
monly furnished as a portion of a complete outfit such as 



Measuring Tools 



397 



outlined at Fig. 173. That shown has two sizes of die- 
stock, a tap wrench, eight assorted dies, eight assorted 
taps, and a small screw driver for adjusting the die. An 
automobile repair shop should be provided with three 
different sets of taps and dies, as three different stand- 
ards for the bolts and nuts are used in fastening auto- 
mobile components. These are the American, metric 




Fig. 173. — Useful Outfit of Taps and Dies for the Engine Repair Shop. 

(used on foreign engines), and the S. A. E. standard 
threads. A set of pipe dies and taps will also be found 
useful. 

MEASURING TOOLS 

The tool outfit of the machinist or the mechanic who 
aspires to do machine work must include a number of 
measuring tools which are not needed by the floor man or 
one who merely assembles and takes apart the finished 
pieces. The machinist who must convert raw material 
into finished products requires a number of measuring 
tools, some of which are used for taking only approxi- 
mate measurements, such as calipers and scales, while 
others are intended to take very accurate measurements, 
such as the Vernier and the micrometer. A number of 
common forms of calipers are shown at Fig. 174. These 
are known as inside or outside calipers, depending upon 
the measurements they are intended to take. That at A 



398 



Aviation Engines 



is an inside caliper, consisting of two legs, A and D, and 
a gauging piece, B, which can be locked to leg A, or re- 
leased from that member by the screw, C. The object of 
this construction is to permit of measurements being 
taken at the bottom of a two diameter hole, where the 
point to be measured is of larger diameter than the por- 
tion of the hole through which the calipers entered. It 
will be apparent that the legs A and D must be brought 
close together to pass through the smaller holes. This 




Fig. 174. — Common Forms of Inside and Outside Calipers. 



may be done without losing the setting, as the guide bar 
B will remain in one position as determined by the size 
of the hole to be measured, while the leg A may be swung 
in to clear the obstruction as the calipers are lifted out. 
When it is desired to ascertain the measurements the leg 
A is pushed back into place into the slotted portion of the 
guide B, and locked by the clamp screw C. A tool of this 
form is known as an internal transfer caliper. 

The form of caliper shown at B is an outside caliper. 
Those at C and D are special forms for inside and out- 



Measuring Tools 399 

side work,' the former being used, if desired, as a divider, 
while the latter may be employed for measuring the 
walls of tubing. The calipers at E are simple forms, 
having a friction joint to distinguish them from the spring 
calipers shown at B, C and D. In order to permit of 
ready adjustment of a spring caliper, a split nut as shown 
at G- is sometimes used. A solid nut caliper can only be 
adjusted by screwing the nut in or out on the screw, 
which may be a tedious process if the caliper is to be set 
from one extreme to the other several times in succession. 
With a slip nut as shown at Gr it is possible to slip it 
from one end of the thread to the other without turning 
it, and of locking it in place at any desired point by 
simply allowing the caliper leg to come in contact with 
it. The method of adjusting a spring caliper is shown 
at Fig. 174, H. 

Among the most common of the machinist's tools are 
those used for linear measurements. The usual forms are 
shown in group, Fig. 175. The most common tool, which 
is widely known, is the carpenter's folding two-foot rule 
or the yardstick. While these are very convenient for 
taking measurements where great accuracy is not re- 
quired, the machinist must work much more accurately 
than the carpenter, and the standard steel scale which is 
shown at D, is a popular tool for the machinist. The 
steel scale is in reality a graduated straight edge and 
forms an important part of various measuring tools. 
These are made of high grade steel and vary from 1 to 
48 inches in length. They are carefully hardened in order 
to preserve the graduations, and all surfaces and edges 
are accurately ground to insure absolute parallelism. The 
graduations on the high grade scales are produced with 
a special device known as a dividing engine, but on 
cheaper scales, etching suffices to provide a fairly accurate 
graduation. The steel scales may be very thin and flex- 
ible, or may be about an eighth of an inch thick on the 
twelve-inch size, which is that commonly used with com- 
bination squares, protractors and other tools of that 



400 



Aviation Engines 



nature. The repairman's scale should be graduated both 
with the English system, in which the inches are di- 
vided into eighths, sixteenths, thirty- secondths and sixty- 



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Fig. 175. — Measuring Appliances for the Machinist and Floor Man. 

fourths, and also in the metric system, divided into milli- 
meters and centimeters. Some machinists use scales 
graduated in tenths, twentieths, fiftieths and hundredths. 



Measuring Instruments 401 

This is not as good a system of graduation as the more 
conventional one first described. 

Some steel scales are provided with a slot or groove 
cut the entire length on one side and about the center of 
the scales. This permits the attachment of various fit- 
tings such as the protractor head, which enables the ma- 
chinist to measure angles, or in addition the heads convert 
the scale into a square or a tool permitting the accurate 
bisecting of pieces of circular section. Two scales are 
sometimes joined together to form a right angle, such as 
shown at Fig. 175, C. This is known as a square and is 
very valuable in ascertaining the truth of vertical pieces 
that are supposed to form a right angle with a base piece. 

The Vernier is a device for reading finer divisions on 
a scale than those into which the scale is divided. Sixty- 
fourths of an inch are about the finest division that can 
be read accurately with the naked eye. When fine work 
is necessary a Vernier is employed. This consists essen- 
tially of two rules so graduated that the true scale has 
each inch divided into ten equal parts, the upper or Ver- 
nier portion has ten divisions occupying the same space 
as nine of the divisions of the true scale. It is evident, 
therefore, that one of the divisions of the Vernier is equal 
to nine-tenths of one of those on the true scale. If the 
Vernier scale is moved to the right so that the gradua- 
tions marked "1" shall coincide, it will have moved one- 
tenth of a division on the scale or one-hundredth of an 
inch. When the graduations numbered 5 coincide the 
Vernier will have moved five-hundredths of an inch ; when 
the lines marked and 10 coincide, the Vernier will have 
moved nine-hundredths of an inch, and when 10 on the 
Vernier comes opposite 10 on the scales, the upper rule 
will have moved ten-hundredths of an inch, or the whole 
of one division on the scale. By this means the scale, 
though it may be graduated only to tenths of an inch, 
may be accurately set at points with positions expressed 
in hundredths of an inch. When graduated to read in 
thousandths, the true scale is divided into fifty parts and 



402 



Aviation Engines 



the Vernier into twenty parts. Each division of the Ver- 
nier is therefore equal to nineteen-twentieths of one of 
the true scale. If the Vernier be moved so the lines of 
the first division coincide, it will have moved one-twen- 
tieth of one-fiftieth, or .001 inch. The Vernier principle 
can be readily grasped by studying the section of the 
Vernier scale and true scale shown at Fig. 176, A. 

The caliper scale which is shown at Fig. 175, A, per- 
mits of taking the over-all dimension of any parts that 



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5lN. 2 IN. I&IN. llM. hlH. 



Fig. 176. — At Left, Special Form of Vernier Caliper for Measuring Gear 
Teeth; at Right, Micrometer for Accurate Internal Measurements. 

will go between the jaws. This scale can be adjusted very 
accurately by means of a fine thread screw attached to a 
movable jaw and the divisions may be divided by eye 
into tAvo parts if one sixty-fourth is the smallest of the 
divisions. A line is indicated on the movable jaw and 
coincides with the graduations on the scale. As will be 
apparent, if the line does not coincide exactly with one 
of the graduations it will be at some point between the 
lines and the true measurement may be approximated with- 
out trouble. 

A group of various other measuring tools of value to 
the machinist is shown at Fig. 177. The small scale at A 
is termed a "center gauge," because it can be used to test 



Measuring Tools 



403 



"the truth of the taper of either a male or female lathe 
center. The two smaller nicks, or v's, indicate the shape 
of a standard thread, and may be nsed as a gnide for 
grinding the point of a thread-cntting tool. The cross 
level which is shown at B is of marked utility in erecting, 
as it will indicate absolutely if the piece it is used to test 




Fig. 177. — Measuring Appliances of Value in Airplane Repair Work. 

is level. It will indicate if the piece is level along its 
width as well as its length. 

A very simple attachment for use with a scale that 
enables the machinist to scribe lines along the length of 
a cylindrical piece is shown at Fig. 177, C. These are 
merely small wedge-shaped clamps having an angular 
face to rest upon the bars. The thread pitch gauge which 
is shown at Fig. 177, D, is an excellent pocket tool for the 
mechanic, as it is often necessary to determine without 
loss of time the pitch of the thread on a bolt or in a nut. 
This consists of a number of leaves having serrations on 
one edge corresponding to the standard thread it is to be 



404 Aviation Engines 

used in measuring. The tool shown gives all pitches up 
to 48 threads per inch. The leaves may be folded in out 
of the way when not in use, and their shape admits of 
their being used in any position without the remainder 
of the set interfering with the one in use. The fine pitch 
gauges have slim, tapering leaves of the correct shape to 
be used in finding the pitch of small nuts. As the tool is 
round when the leaves are folded back out of the way, it 
is an excellent pocket tool, as there are no sharp corners 
to wear out the pocket. Practical application of a Ver- 
nier having measuring heads of special form for measur- 
ing gear teeth is shown at Fig. 176, A. As the action of 
this tool has been previously explained, it will not be 
necessary to describe it further. 

MICROMETER CALIPERS AND THEIR USE 

Where great accuracy is necessary in taking measure- 
ments the micrometer caliper, which in the simple form 
will measure easily .001 inch (one-thousandth part of an 
inch) and when fitted with a Vernier that will measure 
.0001 inch (one ten- thousandth part of an inch), is used. 
The micrometer may be of the caliper form for measur- 
ing outside diameters or it may be of the form shown at 
Fig. 176, B, for measuring internal diameters. The opera- 
tion of both forms is identical except that the internal 
micrometer is placed inside of the bore to be measured 
while the external form is used just the same as a caliper. 
The form outlined will measure from one and one-half to 
six and a half inches as extension points are provided to 
increase the range of the instrument. The screw has a 
movement of one-half inch and a hardened anvil is placed 
in the end of the thimble in order to prevent undue wear 
at that point. The extension points or rods are accurately 
made in standard lengths and are screwed into the body 
of the instrument instead of being pushed in, this insur- 
ing firmness and accuracy. Two forms of micrometers 
for external measurements are shown at Fig. 178. The 



Micrometers and Their Use 



405 



top one is graduated to read in thousandths of an inch, 
while the lower one is graduated to indicate hundredths 
of a millimeter. The mechanical principle involved in the 
construction of a micrometer is that of a screw free to 




i i i fifl i mmi 




Miii 



Micrometer Grocfv&Ted 
in Thousandths of 
fJn /nch 



Oevefopment of 
= Scofe on do ml 
= of inch Micrometer 







Oeue/oprnent of 
Scale on Borret 
of Metric Micrometer 



/iicromofcr Gr4ai<afe<{ 
tN r/v/x/redtys of 
ft Mtt/imeter 



iiiiiiiiiun 



Fig. 178.— Standard Forms of Micrometer Caliper for External Measure- 
ments. 

move in a fixed nut. An opening to receive the work to 
be measured is provided by the backward movement of the 
thimble which turns the screw and the size of the opening 
is indicated by the graduations on the barrel. 



406 Aviation Engines 

The article to be measured is placed between the anvil 
and spindle, the frame being held stationary while the 
thimble is revolved by the thnmb and finger. The pitch 
of the screw thread on the concealed part of the spindle 
is 40 to an inch. One complete revolution of the spindle, 
therefore, moves it longitudinally one-fortieth, or twenty- 
five thousandths of an inch. As will be evident from the 
development of the scale on the barrel of the inch mi- 
crometer, the sleeve is marked with forty lines to the 
inch, each of these lines indicating twenty-five thou- 
sandths. The thimble has a beveled edge which is gradu- 
ated into twenty-five parts. "When the instrument is 
closed the graduation on the beveled edge of the thimble 
marked should correspond to the line on the barrel. 
If the micrometer is rotated one full turn the opening 
between the spindle and anvil will be .025 inch. If the 
thimble is turned only one graduation, or one twenty- 
fifth of a revolution, the opening between the spindle and 
anvil will be increased only by .001 inch (one-thousandth 
of an inch). 

As many of the dimensions of the airplane parts, 
especially of those of foreign manufacture or such parts 
as ball and roller bearings, are based on the metric sys- 
tem, the competent repairman should possess both inch 
and metric micrometers in order to avoid continual refer- 
ence to a table of metric equivalents. With a metric mi- 
crometer there are fifty graduations on the barrel, these 
representing .01 of a millimeter, or approximately .004 
inch. One full turn of the barrel means an increase of 
half a millimeter, or .50 mm. (fifty one-hundredths). As 
it takes two turns to augment the space between the anvil 
and the stem by increments of one millimeter, it will be 
evident that it would not be difficult to divide the spaces 
on the metric micrometer thimble in halves by the eye, 
and thus the average workman can measure to .0002 inch 
plus or minus without difficulty. As set in the illustra- 
tion, the metric micrometers show a space of 13.5 mm., 
or about one millimeter more than half an inch. The 



Micrometers and Their Use 407 

inch micrometer shown is set to five-tenths or five hun- 
dred one-thousandths or one-half inch. A little study of 
the foregoing matter will make it easy to understand the 
action of either the inch or metric micrometer. 

Both of the micrometers shown have a small knurled 
knob at the end of the barrel. This controls the ratchet 
stop, which is a device that permits a ratchet to slip by 
a pawl when more than a certain amount of pressure is 
applied, thereby preventing the measuring spindle from 
turning further and perhaps springing the instrument. A 
simple rule that can be easily memorized for reading the 
inch micrometer is to multiply the number of vertical 
divisions on the sleeve by 25 and add to that the number 
of divisions on the bevel of the thimble reading from the 
zero to the line which coincides with the horizontal line on 
the sleeve. For example: if there are ten divisions visi- 
ble on the sleeve, multiply this number by 25, then add 
the number of divisions shown on the bevel of the thim- 
ble, which is 10. The micrometer is therefore opened 
10 x 25 equals 250 plus 10 equals 260 thousandths. 

Micrometers are made in many sizes, ranging from 
those having a maximum opening of one inch to special 
large forms that will measure forty or more inches. 
While it is not to be expected that the repairman mil have 
use for the big sizes, if a caliper having a maximum 
opening of six inches is provided with a number of ex- 
tension rods enabling one to measure smaller objects, 
practically all of the measuring needed in repairing en- 
gine parts can be made accurately. Two or three smaller 
micrometers having a maximum range of two or three 
inches will also be found valuable, as most of the measure- 
ments will be made with these tools which will be much 
easier to handle than the larger sizes. 

TYPICAL TOOL OUTFITS 

The equipment of tools necessary for repairing air- 
plane engines depends entirely upon the type of the power 



408 Aviation Engines 

plant and while the common hand tools can be used on 
all forms, the work is always facilitated by having special 
tools adapted for reaching the nuts and screAvs that would 
be hard to reach otherwise. Special spanners and socket 
wrenches are very desirable. Then again, the na'ture of 
the work to be performed must be taken into considera- 
tion. Rebuilding or overhauling an engine calls for con- 
siderably more tools than are furnished for making field 
repairs or minor adjustments. A complete set of tools 
supplied to men working on Curtiss OX-2 engines and 
JN-4 training biplanes is shown at Fig. 179. ,The tools 
are placed in a special. box provided with a hinged cover 
and are arranged in the systematic manner outlined. 
The various tools and supplies shown are: A, hacksaw 
blades; B, special socket wrenches for engine bolts and 
nuts; C, ball pein hammers, four sizes; D, five assorted 
sizes of screw drivers ranging from very long for heavy 
work to short and small for fine work; E, seven pairs of 
pliers including combination in three sizes, two pairs of 
cutting pliers and one round nose; F, two split pin ex- 
tractors and spreaders; Gr, wrench set including three 
adjustable monkey wrenches, one Stilson or pipe wrench, 
five sizes adjustable end wrenches and ten double end 
S wrenches; H, set of files, including flat, three cornered 
and half round; I, file brush; J, chisel and drift pin; 
K, three small punches or drifts; L, hacksaw frame; M, 
soldering copper; N, special spanners for propeller re- 
taining nuts; 0, special spanners; P, socket wrenches, 
long handle; Q, long handle, stiff bristle brushes for 
cleaning motor; R, gasoline blow torch; S, hand drill; 
T, spools of safety wire ; U, flash lamp ; V, special puller 
and castle wrenches; W, oil can; X, large adjustable 
monkey wrench; Y, washer and gasket cutter; Z, ball of 
heavy twine. In addition to the tools, various supplies, 
such as soldering acid, solder, shellac, valve grinding com- 
pound, bolts and nuts, split pins, washers, wood screws, 
etc., are provided. 




409 



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412 Aviation Engines 

The special tools and fixtures recommended by the 
Hall-Scott Company for work on their engines are clearly 
shown at Fig. 180. All tools are numbered and their uses 
may be clearly understood by reference to the illustra- 
tion and explanatory list given on pages 410 and 411. 



OVEKHAULING AIRPLANE ENGINES 

After an airplane engine has been in use for a period 
ranging from 60 to 80 hours, depending upon the type, 
it is necessary to give it a thorough overhauling before 
it is returned to service. To do this properly, the engine 
is removed from the fuselage and placed on a special sup- 
porting stand, such as shown at Fig. 181, so it can be 
placed in any position and completely dismantled. With 
a stand of this kind it is as easy to work on the bottom 
of the engine as on the top and every part can be in- 
stantly reached. The crank-case shown in place in illus- 
tration is in a very convenient position for scraping in 
the crank-shaft bearings. 

In order to look over the parts of an engine and to 
restore the worn or defective components it is necessary 
to take the engine entirely apart, as it is only when the 
power plant is thoroughly dismantled that the parts can 
be inspected or measured to determine defects or wear. 
If one is not familiar with the engine to be inspected, 
even though the work is done by a repairman of experi- 
ence, it will be found of value to take certain precautions 
when dismantling the engine in order to insure that all 
parts will be replaced in the same position they occupied 
before removal. There are a number of ways of identi- 
fying the parts, one of the simplest and surest being to 
mark them with steel numbers or letters or with a series 
of center punch marks in order to retain the proper rela- 
tion when reassembling. This is of special importance 
in connection with dismantling multiple cylinder engines 
as it is vital that pistons, piston rings, connecting rods, 
valves, and other cylinder parts be always replaced in 




413 



A 



414 



Aviation Engines 



the same cylinder from which they were removed, be- 
cause it is uncommon to find equal depreciation in all 
cylinders. Some repairmen use small shipping tags to 
identify the pieces. This can be criticised because the 
tags may become detached and lost and the identity of 




Fig. 181. — Special Stand to Make Motor Overhauling Work Easier. 

the piece mistaken. If the repairing is being done in a 
shop where other engines of the same make are being 
worked on, the repairman should be provided with a large 
chest fitted with a lock and key in which all of the smaller 
parts, such as rods, bolts and nuts, valves, gears, valve 
springs, cam-shafts, etc., may be stored to prevent the 
possibility of confusion with similar members of other 



Dismantling an Engine 415 

engines. All parts should be thoroughly cleaned with 
gasoline or in the potash kettle as removed, and wiped 
clean and dry. This is necessary to show wear which will 
be evidenced by easily identified indications in cases 
where the machine has been used for a time, but in others, 
the deterioration can only be detected by delicate measur- 
ing instruments. 

In taking down a motor the smaller parts and fittings 
such as spark-plugs, manifolds and wiring should be re- 
moved first. Then the more important members such as cyl- 
inders may be removed from the crank-case to give access 
to the interior and make possible the examination of the 
pistons, rings and connecting rods. After the cylinders are 
removed the next operation is to disconnect the connect- 
ing rods from the crank-shaft and to remove them and 
the pistons attached as a unit. Then the crank-case is 
dismembered, in most cases by removing the bottom half 
or oil sump, thus exposing the main bearings and crank- 
shaft. The first operation is the removal of the inlet and 
exhaust manifolds. In some cases the manifolds are 
cored integral with the cylinder head casting and it is 
merely necessary to remove a short pipe leading from the 
carburetor to one inlet opening and the exhaust pipe from 
the outlet opening common to all cylinders. In order to 
remove the carburetor it is necessary to shut off the gaso- 
line supply at the tank and to remove the pipe coupling 
at the float chamber. It is also necessary to disconnect 
the throttle operating rod. After the cylinders are re- 
moved and before taking the crank-case apart it is well 
to remove the water pump and magneto. The wiring on 
most engines of modern development is carried in con- 
duits and usually releasing two or three minor fastenings 
will permit one to take off the plug wiring as a unit. 
The wire should be disconnected from both spark-plugs 
and magneto distributor before its removal. When the 
cylinders are removed, the pistons, piston rings, and con- 
necting rods are clearly exposed and their condition may 
be readily noticed. 



416 Aviation Engines 

Before disturbing the arrangement of the timing 
gears, it is important that these be marked so that they 
will be replaced in exactly the same relation as intended 
by the engine designer. If the gears are properly marked 
the valve timing and magneto setting will be undisturbed 
when the parts are replaced after overhanling. With the 
cylinders off, it is possible to ascertain if there is any 
undue wear present in the connecting rod bearings at 
either the wrist pin or crank-pin ends and also to form 
some idea of the amount of carbon deposits on the piston 
top and back of the piston rings. Any wear of the tim- 
ing gears can also be determined. The removal of the 
bottom plate of the engine enables the repairman to see 
if the main bearings are w T orn unduly. Often bearings 
may be taken up sufficiently to eliminate all looseness. In 
other cases they may be worn enough so that careful 
refitting will be necessary. Where the crank-case is 
divided horizontally into two portions, the upper one 
serving as an engine base to which the cylinders and in 
fact all important working parts are attached, the lower 
portion performs the functions of an oil container and 
cover for the internal mechanism. This is the construc- 
tion generally followed. 



DEFECTS IF CYLINDERS 

After the cylinders have been removed and stripped 
of all fittings, they should be thoroughly cleaned and then 
carefully examined for defects. The interior or bore 
should be looked at with a view of finding score marks, 
grooves, cuts or scratches in the interior, because there 
are many faults that may be ascribed to depreciation at 
this point. The cylinder bore may be worn out of round, 
which can only be determined by measuring with an in- 
ternal caliper or dial indicator even if the cylinder bore 
shows no sign of wear. The flange at the bottom of the 
cylinder by which it is held to the engine base may be 
cracked. The water jacket wall may have opened up due 



Defects in Cylinders 417 

to freezing of the jacket water at some time or other or it 
may be filled with scale and sediment dne to the use of 
impure cooling water. The valve seat may be scored or 
pitted, while the threads holding the valve chamber cap 
may be worn so that the cap will not be a tight fit. The 
detachable head construction makes it possible to remove 
that member and obtain ready access to the piston tops 
for scraping out carbon without taking the main cylinder 
portion from the crank-case. When the valves need grind- 
ing the head may be removed and carried to the bench 
where the work may be performed with absolute assurance 
that none of the valve grinding compound will penetrate 
into the interior of the cylinder as is sometimes unavoid- 
able with the I-head cylinder. If the cylinder should be 
scored, the water jacket and combustion head may be 
saved and a new cylinder casting purchased at consider- 
ably less cost than that of the complete unit cylinder. 

The detachable head construction has only recently 
been applied on airplane engines, though it was one ol 
the earliest forms of automobile engine construction. In 
the early days it was difficult to procure gaskets or pack- 
ings that would be both gas and water tight. The sheet 
asbestos commonly used was too soft and blew out read- 
ily. Besides a new gasket had to be made every time 
the cylinder head was removed. Woven wire and asbestos 
packings impregnated with rubber, red lead, graphite and 
other filling materials were more satisfactory than the 
soft sheet asbestos, but were prone to burn out if the 
water supply became low. Materials such as sheet copper 
or brass proved to be too hard to form a sufficiently yield- 
ing packing medium that would allow for the inevitable 
slight inaccuracies in machining the cylinder head and 
cylinder. The invention of the copper-asbestos gasket, 
which is composed of two sheets of very thin, soft copper 
bound together by a thin edging of the same material 
and having a piece of sheet asbestos interposed solved 
this problem. Copper-asbestos packings form an effec- 
tive seal against leakage of water and a positive reten- 



418 Aviation Engines 

tion means for keeping the explosion pressure in the 
cylinder. The great advantage of the detachable head is 
that it permits of very easy inspection of the piston tops 
and combustion chamber and ready removal of carbon 
deposits. 

CARBON DEPOSITS, THEIR CAUSE AND PREVENTION 



Most authorities agree that carbon is the result of 
imperfect combustion of the fuel and air mixture as well 
as the use of lubricating oils of improper flash point. 
Lubricating oils that work by the piston rings may be- 
come decomposed by the great heat in the combustion 
chamber, but at the same time one cannot blame the lubri- 
cating oil for all of the carbon deposits. There is little 
reason to suspect that pure petroleum oil of proper body 
will deposit excessive amounts of carbon, though if the 
oil is mixed with castor oil, which is of vegetable origin, 
there would be much carbon left in the interior of the 
combustion chamber. Fuel mixtures that are too rich in 
gasoline also produce these undesirable accumulations. 

A very interesting chemical analysis of a sample of 
carbon scraped from the interior of a motor vehicle en- 
gine shows that ordinarily the lubricant is not as much 
to blame as is commonly supposed. The analysis was 
as follows: 

Oil 14.3% 

Other combustible matter 17.9 

Sand, clay, etc 24.8 

Iron oxide 24.5 

Carbonate of lime 8.9 

Other constituents 9.6 

It is extremely probable that the above could be di- 
vided into two general classes, these being approximately 
32.2% oil and combustible matter and a much larger 
proportion, or 67.8% of earthy matter. The presence of 
such a large percentage of earthy matter is undoubtedly 
due to the impurities in the air, such as road dust which 



Removal of Carbon Deposits 419 

has been sucked in through the carburetor. The fact that 
over 17% of the matter which is combustible was not of 
an oily nature lends strong support to this view. There 
would not be the amount of earthy material present in 
the carbon deposits of an airplane engine as above stated 
because the air is almost free from dust at the high alti- 
tudes planes are usually flown. One could expect to find 
more combustible and less earthy matter and the carbon 
would be softer and more easily removed. It is very good 
practice to provide a screen on the air intake to reduce 
the amounts of dust sucked in with the air as well as 
observing the proper precautions relative to supplying 
the proper quantities of air to the mixture and of not 
using any more oil than is needed to insure proper lubri- 
cation of the internal mechanism. 



USE OF CARBON SCRAPERS 

It is not unusual for one to hear an aviator complain 
that the engine he operates is not as responsive as it was 
when new after he has run it but relatively few hours. 
There does not seem to be anything actually wrong with 
the engine, yet it does not respond readily to the throttle 
and is apt to overheat. While these symptoms denote a 
rundown condition of the mechanism, the trouble is often 
due to nothing more serious than accumulations of car- 
bon. The remedy is the removal of this matter out of 
place. The surest way of cleaning the inside of the motor 
thoroughly is to remove the cylinders, if these members 
are cast integrally with the head or of removing the head 
member if 'that is a separate casting, to expose all parts. 

In certain forms of cylinders, especially those of the 
L form, it is possible to introduce simple scrapers down 
through the valve chamber cap holes and through the 
spark-plug hole if this component is placed in the cylin- 
der in some position that communicates directly to the 
interior of the cylinder or to the piston top. No claim 
can be made for originality or novelty of this process as 



420 Aviation Engines 

is has been used for many years on large stationary en- 
gines. The first step is to dismantle the inlet and ex- 
haust piping and remove the valve caps and valves, al- 
though if the deposit is not extremely hard or present 
in large quantities one can often manipulate the scrapers 
in the valve cap openings without removing either the 
piping or the valves. Commencing with the first cylinder, 
the crank-shaft is turned till the piston is at the top of 
its stroke, then the scraper may be inserted, and the 
operation of removing the carbon started by drawing the 
tool toward the opening. As this is similar to a small 
hoe, the cutting edge will loosen some of the carbon and 
will draw it toward the opening. A swab is made of a 
piece of cloth or waste fastened at the end of a wire and 
well soaked in kerosene to clean out the cylinder. 

"When available, an electric motor with a length of 
flexible shaft and a small circular cleaning brush having 
wire bristles can be used in the interior of the engine. 
The electric motor need not be over one-eighth horse- 
power running 1,200 to 1,600 E. P. M., and the wire brush 
must, of course, be of such size that it can be easily in- 
serted through the valve chamber cap. The flexible shaft 
permits one to reach nearly all parts of the cylinder in- 
terior without difficulty and the spreading out and flatten- 
ing of the brush insures that considerable surface will be 
covered by that member. 

BURNING OUT CARBON WITH OXYGEN 

A process of recent development that gives very good 
results in removing carbon without disassembling the 
motor depends on the process of burning out that ma- 
terial by supplying oxygen to support the combustion 
and to make it energetic. A number of concerns are al- 
ready offering apparatus to accomplish this work, and in 
fact any shop using an autogenous welding outfit may 
use the oxygen tank and reducing valve in connection 
with a simple special torch for burning the carbon. Ke- 



Carbon Removal 



421 



suits have demonstrated that there is little danger of 
damaging the motor parts, and that the cost of oxygen 
and labor is much lower than the old method of removing 
the cylinders and scraping the carbon out, as well as 
being very much quicker than the alternative process of 
using carbon solvent. The only drawback to this system 
is that there is no absolute insurance that every particle 
of carbon will be removed, as small protruding particles 
may be left at* points that the flame does not reach and 



Spark P/ug 



.■Water Space 



>n Carbon- ••---t-:; 



i Piston 



Where Carbon Deposits 
collect in Combustion Head 




Torch 



Valve Cap 
Mole, 



Trigger Valve 

C 

Main 
Valve 



Piston-' 

Cylinder--'" 
■Oxygen Tank 




Nose 



Pressure 
Regulator 



Pig. 182. — Showing Where Carbon Deposits Collect in Engine Combustion 
Chamber, and How to Burn Them Out with the Aid of Oxygen. A — 
Special Torch. B— Torch Coupled to Oxygen Tank. C— Torch in Use. 



cause pre-ignition and consequent pounding, even after 
the oxygen treatment. It is generally known that carbon 
will burn in the presence of oxygen, which supports com- 
bustion of all materials, and this process takes advantage 
of this fact and causes the gas to be injected into the 
combustion chamber over a flame obtained by a match or 
wax taper. 

It is suggested by those favoring this process that 
the night before the oxygen is to be used the engine be 
given a conventional kerosene treatment. A half tumbler 
full of this liquid or of denatured alcohol is to be poured 



422 Aviation Engines 

into each cylinder and permitted to remain there over 
night. As a precaution against fire, the gasoline is shut 
off from the carburetor before the torch is inserted in 
the cylinder and the motor started so that the gasoline in 
the pipe and carburetor float chamber will be consumed. 
Work is done on one cylinder at a time. A note of cau- 
tion was recently sounded by a prominent spark-plug 
manufacturer recommending that the igniter member be 
removed from the cylinder in order not to injure * it by 
the heat developed. The outfits on the market consist 
of a special torch having a trigger controlled valve and 
a length of flexible tubing such as shown at Fig. 182, A, 
and a regulating valve and oxygen tank as shown at B. 
The gauge should be made to register about twelve 
pounds pressure. 

The method of operation is very simple and is out- 
lined at C. The burner tube is placed in the cylinder and 
the trigger valve is opened and the oxygen permitted to 
circulate in the combustion chamber. A lighted match 
or wax taper is dropped in the chamber and the injector 
tube is moved around as much as possible so as to cover 
a large area. The carbon takes fire and burns briskly in 
the presence of the oxygen. The combustion of the car- 
bon is accompanied by sparks and sometimes by flame if 
the deposit is of an oily nature. Once the carbon begins 
to burn the combustion continues without interruption as 
long as the oxygen flows into the cylinder. Full instruc- 
tions accompany each outfit and the amount of pressure 
for which the regulator should be set depends upon the 
design of the torch and the amount of oxygen contained 
in the storage tank. 

REPAIRING SCORED CYLINDERS 

If the engine has been run at any time without ade- 
quate lubrication, one or more of the cylinders may be 
found to have vertical scratches running up and down 
the cylinder walls. The depth of these will vary accord- 



Repairing Scored Cylinders 423 

ing to the amount of time the cylinder was without lubri- 
cation, and if the grooves are very deep the only remedy 
is to purchase a new member. Of course, if sufficient 
stock is available in the cylinder walls, the cylinders may 
be rebored and new pistons which are oversize, i.e., larger 
than standard, may be fitted. Where the scratches are 
not deep they may be ground out with a high speed emery 
wheel or lapped out if that type of machine is not avail- 
able. Wrist pins have been known to come loose, espe- 
cially when these are retained by set screws that are not 
properly locked, and as wrist-pins are usually of hard- 
ened steel it will be evident that the sharp edge of that 
member can act as a cutting tool and make a pronounced 
groove in the cylinder. Cylinder grinding is a job that 
requires skilled mechanics, but may be accomplished on 
any lathe fitted with an internal grinding attachment. 
While automobile engine cylinders usually have sufficient 
wall thickness to stand reboring, those of airplane engines 
seldom have sufficient metal to permit of enlarging the 
bore very much by a boring tool. A few thousandths of 
an inch may be ground out without danger, however.. 
An airplane engine cylinder with deep grooves must be 
scrapped as a general rule. 

Where the grooves in the cylinder are not deep or 
where it has warped enough so the rings do not bear 
equally at all parts of the cylinder bore, it is possible to 
obtain a fairly accurate degree of finish by a lapping pro- 
cess in which an old piston is coated with a mixture of 
fine emery and oil and is reciprocated up and down in the 
cylinder as well as turned at the same time. This may 
be easily done by using a dummy connecting rod having 
only a wrist pin end boss, and of such size at the other 
end so that it can be held in the chuck of a drill press. 
The cylinder casting is firmly clamped on the drill press 
table by suitable clamping blocks, and a wooden block is 
placed in the combustion chamber to provide a stop for 
the piston at its lower extreme position. The back gears 
are put in and the drill chuck is revolved slowly. All the 



424 Aviation Engines 

while that the piston is turning the drill chuck should be 
raised up and down by the hand feed lever, as the best 
results are obtained when the lapping member is given 
a combination of rotary and reciprocating motion. 



VALVE REMOVAL AND INSPECTION 

One of the most important parts of the gasoline en- 
gine and one that requires frequent inspection and refit- 
ting to keep in condition, is the mushroom or poppet valve 
that controls the inlet and exhaust gas flow. In over- 
hauling it is essential that these valves be removed from 
their seatings and examined carefully for various defects 
which will be enumerated at proper time. The problem 
that concerns us now is the best method of removing the 
valve. These are held against the seating in the cylinder 
by a coil spring which exerts its pressure on the cylinder 
casting at the upper end and against a suitable collar 
held by a key at the lower end of the valve stem. In 
order to remove the valve it is necessary to first com- 
press the spring by raising the collar and pulling the 
retaining key out of the valve stem. Many forms of valve 
spring lifters have been designed to permit ready re- 
moval of the valves. 

When the cylinder is of the valve in-the-head form, 
the method of valve removal will depend entirely upon 
the system of cylinder construction followed. In the 
Sturtevant cylinder design it is possible to remove the 
head from the cylinder castings and the valve springs 
may be easily compressed by any suitable means when 
the cylinder head is placed on the work bench where it 
can be easily worked on. The usual method is to place 
the head on a soft cloth with the valves bearing against 
the bench. The valve springs may then be easily pushed 
down with a simple forked lever and the valve stem key 
removed to release the valve spring collar. In the Curtiss 
OX-2 (see Fig. 182%) and Hall-Scott engines it is not 
possible to remove the valves without taking the cylinder 



Valve Removal and Inspection 



425 



off the crank-case, because the valve seats are machined 
directly in the cylinder head and the valve domes are cast 
integrally with the cylinder. This means that if the valves 
need grinding the cylinder must be removed from the 
engine base to provide access to the valve heads which 
are inside of that member, and which cannot be reached 



Exhaust. 

Valve Spring 



Exhaust, Port 




Water 



Cylinder 



Fig. 182y 2 - — Part Sectional View, Showing Valve Arrangement in Cylinder 
of Curtiss OX-2 Aviation Engine. 

from the outside as is true of the L-cylinder construction. 
In the Curtiss VX engines, the valves are carried in de- 
tachable cages which may be removed when the valves 
need attention. 



RESEATING AXD TRUIXG VALVES 

Much has been said relative to valve grinding, and 
despite the mass of information given in the trade prints 



426 Aviation Engines 

it is rather amusing to watch the average repairman or the 
engine user who prides himself on maintaining his own 
motor performing this essential operation. The common 
mistakes are attempting to seat a badly grooved or pitted 
valve head on an equally bad seat, which is an almost 
hopeless job, and of using coarse emery and bearing down 
with all one's weight on the grinding tool with the hope 
of quickly wearing away the rough surfaces. The use of 
improper abrasive material is a fertile cause of failure 
to obtain a satisfactory seating. Valve grinding is not a 
difficult operation if certain precautions are taken before 
undertaking the work. The most important of these is 
to ascertain if the valve head or seat is badly scored or 
pitted. If such is found to be the case no ordinary 
amount of grinding will serve to restore the surfaces. In 
this event the best thing to do is to remove the valve 
from its seating and to smooth down both the valve head 
and the seat in the cylinder before attempt is made to 
fit them together by grinding. Another important pre- 
caution is to make sure that the valve stem is straight, 
and that the head is not warped out of shape. 

A number of simple tools is available at the present 
time for reseating valves, these being outlined at Fig. 
183. That shown at A is a simple fixture for facing off: 
the valve head. The stem is supported by suitable bear- 
ings carried by the body or shank of the tool, and the 
head is turned against an angularly disposed cutter which 
is set for the proper valve seat angle. The valve head 
is turned by a screw-driver, the amount of stock removed 
from the head depending upon the location of the adjust- 
ing screw. Care must be taken not to remove too much 
metal, only enough being taken off to remove the most 
of the roughness. Valves are made in two standard 
tapers, the angle being either 45 or 60 degrees. It is im- 
perative that the cutter blade be set correctly in order 
that the bevel is not changed. A set of valve truing and 
valve-seat reaming cutters is shown at Fig. 183, B. This 
is adaptable to various size valve heads, as the cutter 



Valve Restoration 



42? 



blade D may be moved to correspond to the size of the 
valve head being trued up. These cutter blades are made 



V/ilvc 
Hzao 




Fig. 183. — Tools for Restoring Valve Head and Seats. 

of tool steel and have a bevel at each end, one at 45 de- 
grees, the other at 60 degrees. The valve seat reamer 
shown at G will take any one of the heads shown at F. 



428 Aviation Engines 

It will also take any one of the guide bars shown at H. 
The function of the guide bars is to fit the valve stem 
bearing in order to locate the reamer accurately and to 
insure that the valve seat is machined concentrically with 
its normal center. Another form of valve seat reamer 
and a special wrench used to turn it is shown at C. The 
valve head truer shown at Fig. 183, D, is intended to be 
placed in a vise and is adaptable to a variety of valve 
head sizes. The smaller valves merely fit deeper in the 
conical depression. The cutter blade is adjustable and 
the valve stem is supported by a simple self-centering 
bearing. In operation it is intended that the valve stem, 
which protrudes through the lower portion of the guide 
bearing, shall be turned by a drill press or bit stock while 
the valve head is set against the cutter by pressure of a 
pad carried at the end of a feed screw which is supported 
by a hinged bridge member. This can be swung out of 
place as indicated to permit placing the valve head against 
the cutter or removing it. 

As the sizes of valve heads and stems vary consider- 
ably a "Universal" valve head truing tool must have 
some simple means of centering the valve stem in order 
to insure concentric machining of the valve head. A valve 
head truer which employs an ingenious method of guid- 
ing the valve stem is shown at Fig. 183, E. The device 
consists of a body portion, B, provided with an external 
thread at the top on which the cutter head, A, is screwed. 
A number of steel balls, C, are carried in the grooves 
which may be altered in size by the adjustment nut, F, 
which screws in the bottom of the body portion, B. As 
the nut F is screwed in against the spacer member E, 
the V-grooves are reduced in size and the steel balls, C, 
are pressed out in contact with the valve stem. As the 
circle or annulus is filled with balls in both upper and 
lower portions the stem may be readily turned because 
it is virtually supported by ball bearing guides. When 
a larger valve stem is to be supported, the adjusting nut 
F, is screwed out which increases the size of the grooves 



Valve Grinding Processes 429 

and permits the balls, C, to spread oat and allow the larger 
stem to be inserted. 



YALVE GEIXDIXG PROCESSES 

Mention has been previously made of the importance 
of truing both valve head and seat before attempt is made 
to refit the parts by grinding. After smoothing the valve 
seat the next step is to find some way of turning the valve. 
Yalve heads are usually provided with a screw-driver slot 
passing through the boss at the top of the valve or with 
two drilled holes to take a forked grinding tool. A com- 
bination grinding tool has been devised which may be 
used when either the two drilled holes or the slotted head 
form of valve is to be rotated. This consists of a special 
form of screw driver having an enlarged boss just above 
the blade, this boss serving to support a U-shape piece 
which can be securely held in operative position by the 
clamp screw or which can be turned out of the way if 
the screw driver blade is to be used. 

As it is desirable to turn the valve through a portion 
of a revolution and back again rather than turning it 
always in the same direction, a number of special tools 
has been designed to make this oscillating motion possible 
without trouble. A simple valve grinding tool is shown 
at Fig. 184, C. This consists of a screw-driver blade 
mounted in a handle in such a way that the end may 
turn freely in the handle. A pinion is securely fastened 
to the screw-driver blade shank, and is adapted to fit a 
race provided with a wood handle and guided by a bent 
bearing member securely fastened to the screw-driver 
handle. As the rack is pushed back and forth the pinion 
must be turned first in one direction and then in the other. 

A valve grinding tool patterned largely after a breast 
drill is shown at Fig. 184, D. This is worked in such a 
manner that a continuous rotation of the operating crank 
will result in an oscillating movement of the chuck carry- 
ing the screw-driver blade. The bevel pinions which are 



*30 



Aviation Engines 



used to turn the chuck are normally free unless clutched 
to the chnck stem by the sliding sleeve which must turn 
with the chnck stem and which carries clutching members 




■Screw 
Driver 
Bit 



K Valve Stem 



Fig. 184. — Tools and Processes Utilized in Valve Grinding. 



at each end to engage similar members on the bevel pin- 
ions and lock these to the chnck stem, one at a time. The 
bevel gear carries a cam-piece which moves the clutch 



Valve Grinding Processes 431 

sleeve back and forth as it revolves. This means that the 
pinion giving forward motion of the chuck is clutched to 
the chnck spindle for a portion of a revolution of the 
gear and clutch sleeve is moved back by the cam and 
clutched to the pinion giving a reverse motion of the 
chuck during the remainder of the main drive gear revo- 
lution. 

It sometimes happens that the adjusting screw on the 
valve lift plunger or the valve lift plunger itself when 
L head cylinders are used does not permit the valve head 
to rest against the seat. It will be apparent that unless 
a definite space exists between the end of the valve stem 
and the valve lift plunger that grinding will be of little 
avail because the valve head will not bear properly 
against the abrasive material smeared on the valve seat. 

The usual methods of valve grinding are clearly out- 
lined at Fig. 184. The view at the left shows the method 
of turning the valve by an ordinary screw driver and also 
shows a valve head at A, having both the drilled holes 
and the screw-driver slot for turning the member and two 
special forms of fork-end valve grinding tools. In the 
sectional view shown at the right, the use of the light 
spring between the valve head and the bottom of the valve 
chamber to lift the valve head from the seat whenever 
pressure on the grinding tool is released is clearly indi- 
cated. It will be noted also that a ball of waste or cloth 
is interposed in the passage between the valve chamber 
and the cylinder interior to prevent the abrasive material 
from passing into the cylinder from the valve chamber. 
When a bitstock is used, instead of being given a true 
rotary motion the chuck is merely oscillated through the 
greater part of the circle and back again. It is necessary 
to lift the valve from its seat frequently as the grinding 
operation continues; this is to provide an even distribu- 
tion of the abrasive material placed between the valve 
head and its seat. Only sufficient pressure is given to 
the bitstock to overcome the uplift of the spring and to 
insure that the valve will be held against the seat. Where 



432 Aviation Engines 

the spring is not used it is possible to raise the valve 
from time to time with the hand which is placed under 
the valve stem to raise it as the grinding is carried on. 
It is not always possible to lift the valve in this manner 
when the cylinders are in place on the engine base owing 
to the space between the valve lift plunger and the end 
of the valve stem. In this event the use of the spring as 
shown in sectional view will be desirable. 

The abrasive generally used is a paste made of 
medium or fine emery and lard oil or kerosene. This is 
used until the surfaces are comparatively smooth, after 
which the final polish or finish is given with a paste of 
flour emery, grindstone dust, crocus, or ground glass and 
oil. An erroneous impression prevails in some quarters 
that the valve head surface and the seating must have 
a mirror-like polish. While this is not necessary it is 
essential that the seat in the cylinder and the bevel sur- 
face of the head be smooth and free from pits or scratches 
at the completion of the operation. All traces of the 
emery and oil should be thoroughly washed out of the 
valve chamber with gasoline before the valve mechanism 
is assembled and in fact it is advisable to remove the old 
grinding compound at regular intervals, wash the seat 
thoroughly and supply fresh material as the process is in 
progress. 

The truth of seatings may be tested by taking some 
Prussian blue pigment and spreading a thin film of it 
over the valve seat. The valve is dropped in place and 
is given about one-eighth turn with a little pressure on 
the tool. If the seating is good both valve head and seat 
will be covered uniformly with color. If high spots exist, 
the heavy deposit of color will show these while the low 
spots will be made evident because of the lack of pig- 
ment. The grinding process should be continued until 
the test shows an even bearing of the valve head at all 
points of the cylinder seating. When the valves are held 
in cages it is possible to catch the cage in a vise and to 
turn the valve in any of the ways indicated. It is much 



Depreciation In Valve Systems 433 

easier to clean off the emery and oil and there is abso- 
lutely no danger of getting the abrasive material in the 
cylinder if the construction is such that the valve cage 
or cylinder head member carrying the valve can be re- 
moved from the cylinder. "When valves are held in cages, 
the tightness of the seat may be tested by partially rilling 
the cage with gasoline and noticing how much liquid oozes 
out around the valve head. The degree of moisture pres- 
ent indicates the efficacy of the grinding process. 

The valves of Curtiss OX-2 cylinders are easily 
ground in by using a simple fixture or tool and working 
from the top of the cylinder instead of from the inside. 
A tube having a bore just large enough to go over the 
valve stem is provided with a wooden handle or taped at 
one end and a hole of the same size as that drilled through 
the valve stem is put in at the other. To use, the open 
end of the tube is pushed over the valve stem and a split 
pin pushed through the tube and stem. The valve may 
be easily manipulated and ground in place by oscillating 
in the customary manner. 



DEPRECIATION IN VALVE OPERATING SYSTEMS 

There are a number of points to be watched in the 
valve operating system because valve timing may be seri- 
ously interfered with if there is much lost motion at the 
various bearing points in the valve lift mechanism. The 
two conventional methods of opening valves are shown at 
Fig. 185. That at A is the type employed when the valve 
cages are mounted directly in the head, while the form at 
B is the system used when the valves are located in a 
pocket or extension of the cylinder casting as is the case 
if an L, or T-head cylinder is used. It will be evident 
that there are several points where depreciation may take 
place. The simplest form is that shown at B, and even on 
this there are five points where lost motion may be noted. 
The periphery of the valve opening cam or roller may be 
worn, though this is not likely unless the roller or cam has 



434 



Aviation Engines 



been inadvertently left soft. The pin which acts as a 
bearing for the roller may become worn, this occurring 
qnite often. Looseness may materialize between the bear- 
ing surfaces of the valve lift plunger and the plunger 



Hinge 
Pin 



Fulcrum, 



-Rocker Lever 
.-Spring 




Rocker firm, 
-<--$— -Valve / Fulcrum Pin, 



: Valve Spring. 



Pin, 



W Cage 



Retaining.. 
Nut 



—Valve 
..df-ftB Stem 



""Cam Rollers-..-7 k ^-Pin 
''Valve -Operating Cams...-? 





Fig. 185. — Outlining Points in Valve Operating Mechanism Where Depre- 
ciation is Apt to Exist. 



guide casting, and there may also be excessive clearance 
between the top of the plunger and the valve stem. 

On the form shown at A, there are several parts added 
to those indicated at B. A walking beam or rocker lever 
is necessary to transform the upward motion of the tappet 
rod to a downward motion of the valve stem. The pin 



Depreciation In Valve Systems 435 

on which this member fulcrums may wear as will also the 
other pin acting as a hinge or bearing for the yoke end 
of the tappet rod. It will be apparent that if slight play 
existed at each of the points mentioned it might result in 
a serions diminution of valve opening. Suppose, for ex- 
ample, that there were .005-inch lost motion at each of 
three bearing points, the total lost motion would be .015- 
inch or sufficient to produce noisy action of the valve 
mechanism. "When valve plungers of the adjustable form, 
such as shown at B, are used, the hardened bolt head in 
contact with the end of the valve stem may become hol- 
lowed out on account of the hammering action at that 
point. It is imperative that the top of this member be 
ground off true and the clearance between the valve stem 
and plunger properly adjusted. If the plunger is a non- 
adjustable type it will be necessary to lengthen the valve 
stem by some means in order to reduce the excessive 
clearance. The only remedy for wear at the various 
hinges and bearing pins is to bore the holes out slightly 
larger and to fit new hardened steel pins of larger diam- 
eter. Depreciation between the valve plunger guide and 
the valve plunger is usually remedied by fitting new 
plunger guides in place of the worn ones. If there is 
sufficient stock in the plunger guide casting as is some- 
times the case when these members are not separable from 
the cylinder casting, the guide may be bored out and 
bushed with a light bronze bushing. 

A common cause of irregular engine operation is due to 
a sticking valve. This may be owing to a bent valve stem, 
a weak or broken valve spring or an accumulation of 
burnt or gummed oil between the valve stem and the 
valve stem guide. In order to prevent this the valve stem 
must be smoothed with fine emery cloth and no burrs or 
shoulders allowed to remain on it, and the stem must also 
be straight and at right angles to the valve head. If the 
spring is weak it may be strengthened in some cases by 
stretching it out after annealing so that a larger space 
will exist between the coils and re-hardening. Obviously 



436 Aviation Engines 

if a spring is broken the only remedy is replacement of 
the defective member. 

Mention has been made of wear in the valve stem 
guide and its influence on engine action. When these 
members are an integral part of the cylinder the only 
method of compensating for this wear is to drill the guide 
out and fit a bushing, which may be made of steel tube. 

In some engines, especially those of recent develop- 
ment, the valve stem guide is driven or screwed into the 
cylinder casting and is a separate member which may be 
removed when worn and replaced with a new one. "When 
the guides become enlarged to such a point that con- 
siderable play exists between them and the valve stems, 
they may be easily knocked out or unscrewed. 

PISTON TROUBLES 

If an engine has been entirely dismantled it is very 
easy to examine the pistons for deterioration. "While it 
is important that the piston be a good fit in the cylinder 
it is mainly upon the piston rings that compression de- 
pends. The piston should fit the cylinder with but little 
looseness, the usual practice being to have the piston 
about .001-inch smaller than the bore for each inch of 
piston diameter at the point where the least heat is pres- 
ent or at the bottom of the piston. It is necessary to 
allow more than this at the top of the piston owing to its 
expansion due to the direct heat of the explosion. The 
clearance is usually graduated and a piston that would be 
.005-inch smaller than the cylinder bore at the bottom 
would be about .0065-inch at the middle and .0075-inch at 
the top. If much more play than this is evidenced the 
piston will "slap" in the cylinder and the piston will be 
worn at the ends more than in the center. Aluminum or 
alloy pistons require more clearance than cast iron ones 
do, usually 1.50 times as much. Pistons sometimes warp 
out of shape and are not truly cylindrical. This results 
in the high spots rubbing on the cylinder while the low 



Piston and Ring Troubles 437 

spots will be blackened where a certain amount of gas 
has leaked by. 

Mention has been previously made of the necessity of 
reboring or regrinding a cylinder that has become scored 
or scratched and which allows the gas to leak by the 
piston rings. When the cylinder is ground out, it is nec- 
essary to use a larger piston to conform to the enlarged 
cylinder bore. Most manufacturers are prepared to fur- 
nish over-size pistons, there being four standard over- 
size dimensions adopted by the S. A. E. for rebored 
cylinders. These are .010-inch, .020-inch, .030-inch, and 
.040-inch larger than the original bore. 

The piston rings should be taken out of the piston 
grooves and all carbon deposits removed from the inside 
of the ring and the bottom of the groove. It is important 
to take this deposit out because it prevents the rings 
from performing their proper functions by reducing the 
ring elasticity, and if the deposit is allowed to accumulate 
it may eventually result in sticking and binding of the 
ring, this producing excessive friction or loss of compres- 
sion. "When the rings are removed they, should be tested 
to see if they retain their elasticity and it is also well to 
see that the small pins in some pistons which keep the 
rings from turning around so the joints will not come in 
line are still in place. If no pins are found there is no 
cause for alarm because these dowels are not always 
used. When fitted, they are utilized with rings having a 
butt joint or diagonal cut as the superior gas retaining 
qualities of the lap or step joint render the pins un- 
necessary. 

If gas has been blowing by the ring or if these mem- 
bers have not been fitting the cylinder properly the points 
where the gas passed will be evidenced by burnt, brown 
or roughened portions of the polished surface of the 
pistons and rings. The point where this discoloration 
will be noticed more often is at the thin end of an eccen- 
tric ring, the discoloration being present for about i^-inch 
or %-inch each side of the slot. It may be possible that 



438 Aviation Engines 

the rings were not true when first put in. This made it 
possible for the gas to leak by in small amounts initially 
which increased due to continued pressure until quite a 
large area for gas escape had been created. 



PISTON RING MANIPULATION 

Eemoving piston rings without breaking them is a dif- 
ficult operation if the proper means are not taken, but is 
a comparatively simple one when the trick is known. The 
tools required are very simple, being three strips of thin 
steel about one-quarter inch wide and four or five inches 
long and a pair of spreading tongs made up of one- 
quarter inch diameter keystock tied in the center with a 
copper wire to form a hinge. The construction is such 
that when the hand is closed and the handles brought to- 
gether the other end of the expander spreads out, an 
action just opposite to that of the conventional pliers. 
The method of using the tongs and the metal strips is 
clearly indicated at Fig. 186. At A the ring expander is 
shown spreading the ends of the rings sufficiently to insert 
the pieces of sheet metal between one of the rings and the 
piston. Grasp the ring as shown at B, pressing with the 
thumbs on the top of the piston and the ring will slide off 
easily, the thin metal strips acting as guide members to 
prevent the ring from catching in the other piston grooves. 
Usually no difficulty is experienced in removing the top 
or bottom rings, as these members may be easily expanded 
and worked off directly without the use of a metal strip. 
When removing the intermediate rings, however, the metal 
strips will be found very useful. These are usually made 
by the repairman by grinding the teeth from old hacksaw 
blades and rounding the edges and corners in order to re- 
duce the liability of cutting the fingers. By the use of the 
three metal strips a ring is removed without breaking or 
distorting it and practically no time is consumed in the 
operation. 



Piston Ring Manipulation 439 

FITTING PISTON RINGS 

Before installing new rings, they should be carefully 
fitted to the grooves to which they are applied. The tools 
required are a large piece of fine emery cloth, a thin, flat 
file, a small vise with copper or leaden jaw clips, and a 
smooth hard surface such as that afforded by the top of 
a surface plate or a well planed piece of hard wood. After 
making sure that all deposits of burnt oil and carbon have 
been removed from the piston grooves, three rings are 
selected, one for each groove. The ring is turned all 
around its circumference into the groove it is to fit, which 
can be done without springing it over the piston as the 
outside edge of the ring, may be used to test the width of 
the groove just as well as the inside edge. The ring should 
be a fair fit and while free to move circumferentially there 
should be no appreciable up and down motion. If the 
ring is a tight fit it should be laid edge down upon the 
piece of emery cloth which is placed on the surface plate 
and carefully rubbed down until it fits the groove it is to 
occupy. It is advisable to fit each piston ring individually 
and to mark them in some way to insure that they will be 
placed in the groove to which they are fitted. 

The repairman next turns his attention to fitting the 
ring in the cylinder itself. The ring should be pushed 
into the cylinder at least two inches up from the bottom 
and endeavor should be made to have the lower edge of 
the ring parallel with the bottom of the cylinder. If the 
ring is not of correct diameter, but is slightly larger than 
the cylinder bore, this condition will be evident by the 
angular slots of the rings being out of line or by difficulty 
in inserting the ring if it is a lap joint form. If such is 
the case the ring is removed from the cylinder and placed 
in the vise between soft metal jaw clips. Sufficient metal 
is removed with a fine file from the edges of the ring at 
the slot until the edges come into line and a slight space 
exists between them when the ring is placed into the cylin- 
der. It is important that this space be left between the 



440 



Aviation Engines 



ends, for if this is not done when the ring becomes heated 
the expansion of metal may cause the ends to abut and 
the ring to jam in the cylinder. 

It is necessary to use more than ordinary caution in 
replacing the rings on the piston because they are usually 



..■Thin Metal Strip 



* Piston 
Ring 




Fig. 186. — Method of Removing Piston Rings, and Simple Clamp to Facili- 
tate Insertion of Rings in Cylinder. 



made of cast iron, a metal that is very fragile and liable 
to break because of its brittleness. Special care should 
be taken in replacing new rings as these members are 



Piston Ring Manipulation 441 

more apt to break than old ones. This is probably ac- 
counted for by the heating action on used rings which 
tends to anneal the metal as well as making it less springy. 
The bottom ring should be placed in position first which 
is easily accomplished by springing the ring open enough 
to pass on the piston and then sliding it into place in the 
lower groove which on some types of engines is below 
the wrist pin, whereas in others all grooves are above that 
member. The other members are put in by a reversal of 
the process outlined at Fig. 186, A and B. It is not always 
necessary to use the guiding strips of metal when replac- 
ing rings as it is often possible, by putting the rings on 
the piston a little askew and maneuvering them to pass 
the grooves without springing the ring into them. The 
top ring should be the last one placed in position. 

Before placing pistons in the cylinder one should make 
sure that the slots in the piston rings are spaced equidis- 
tant on the piston, and if pins are used to keep the ring 
from turning one should be careful to make sure that these 
pins fit into their holes in the ring and that they are not 
under the ring at any point. Practically all cylinders are 
chamfered at the lower end to make insertion of piston 
rings easier. The operation of putting on a cylinder cast- 
ing over a piston really requires two pairs of hands, one 
to manipulate the cylinder, the other person to close the 
rings as they enter the cylinder. This may be done very 
easily by a simple clamp member made of sheet brass or 
iron and used to close the ring as indicated at Fig. 186, C. 
It is apparent that the clamp must be adjusted to each 
individual ring and that the split portion of the clamp 
must coincide with the split portion of the ring. The 
cylinder should be well oiled before any attempt is made to 
install the pistons. The engine should be run with more 
than the ordinary amount of lubricant for several hours 
after new piston rings have been inserted. On first start- 
ing the engine, one may be disappointed in that the com- 
pression is even less than that obtained with the old rings. 
This condition will soon be remedied as the rings become 



442 Aviation Engines 

polished and adapt themselves to the contour of the 
cylinder. 

WRIST PIN WEAR 

"While wrist pins are usually made of very tough steel, 
case hardened with the object of wearing out an easily 
renewable bronze bushing in the upper end of the connect- 
ing rod rather than the wrist pin it sometimes happens 
that these members will be worn so that even the re- 
placement of a new bushing in the connecting rod will 
not reduce the lost motion and attendant noise due to a 
loose wrist pin. The only remedy is to fit new wrist pins 
to the piston. Where the connecting rod is clamped to 
the wrist pin and that member oscillates in the piston 
bosses the wear will usually be indicated on bronze bush- 
ings which are pressed into the piston bosses. These are 
easily renewed and after running a reamer through them 
of the proper size no difficulty should be experienced in 
replacing either the old or a new wrist pin depending 
upon the condition of that member. If no bushings are 
provided, as in alloy pistons, the bosses can sometimes 
be bored out and thin bushings inserted, though this is 
not always possible. The alternative is to ream out the 
bosses and upper end of rod a trifle larger after holes are 
trued up and fit oversize wrist pins. 



INSPECTION AND REFITTING OF ENGINE BEARINGS 

While the engine is dismantled one has an excellent 
opportunity to examine the various bearing points in the 
engine crank-case to ascertain if any looseness exists due 
to depreciation of the bearing surfaces. As will be evi- 
dent, both main crank-shaft bearings and the lower end 
of the connecting rods may be easily examined for de- 
terioration. With the rods in place, it is not difficult to 
feel the amount of lost motion by grasping the connect- 
ing rod firmly with the hand and moving it up and down. 
After the connecting rods have been removed and the 



Refitting Engine Bearings 443 

propeller hub taken off the crank-shaft to permit of ready- 
handling, any looseness in the main bearing may be de- 
tected by lifting np on either the front or rear end of 
the crank- shaft and observing if there is any lost motion 
between the shaft journal and the main bearing caps. 
It is not necessary to take an engine entirely apart to 
examine the main bearings, as in most forms these may be 
readily reached by removing the snmp. The symptoms 
of worn main bearings are not hard to identify. If an 
engine knocks regardless of speed or spark-lever position, 
and the trouble is not due to carbon deposits in the com- 
bustion chamber, one may reasonably surmise that the 
main bearings have become loose or that lost motion may 
exist at the connecting rod big ends, and possibly at the 
wrist pins. The main journals of any well resigned en- 
gine are usually proportioned with ample surface and 
will not wear unduly unless lubrication has been neg- 
lected. The connecting rod bearings wear quicker than 
the main bearings owing to being subjected to a greater 
unit stress, and it may be necessary to take these up. 



ADJUSTING MAIN BEARINGS 

When the bearings are not worn enough to require 
refitting the lost motion can often be eliminated by re- 
moving one or more of the thin shims or liners ordinarily 
used to separate the bearing caps from the seat. These 
are shown at Fig. 187, A. Care must be taken that an 
even number of shims of the same thickness are removed 
from each side of the journal. If there is considerable 
lost motion after one or two shims have been removed, 
it will be advisable to take out more shims and to scrape 
the bearing to a fit before the bearing cap is tightened 
up. It may be necessary to clean up the crank-shaft 
journals as these may be scored due to not having re- 
ceived clean oil or having had bearings seize upon them. 
It is not difficult to true up the crank-pins or main jour- 
nals if the score marks are not deep. A fine file and 



Shims, 




..-Emery Cloth 



Minding 
' ' -Nut 



Bearing 
Cop....-'' A 



Vise-' 



Lead Blocks-- 
B 
C// ^x Crankshaft 




Handle Edge, 

Section, 



Bench-' 




V /=^ <^i 



Fig. 187. — Tools and Processes Used in Refitting Engine Bearings. 

444 



Refitting Engine Bearings 445 

emery cloth may be used, or a lapping tool such as de- 
picted at Fig. 187, B. The latter is preferable because 
the file and emery cloth will only tend to smooth the sur- 
face while the lap will have the effect of restoring the 
crank to proper contour. 

A lapping tool may be easily made, as shown at B, the 
blocks being of lead or hard wood. As the width of these 
are about half that of the crank-pin the tool may be 
worked from side to side as it is rotated. An abrasive 
paste composed of fine emery powder and oil is placed 
between the blocks, and the blocks are firmly clamped to 
the crank-pin. As the lead blocks bed down, the wing 
nut should be tightened to insure that the abrasive will be 
held with some degree of pressure against the shaft. A 
liberal supply of new abrading material is placed between 
the lapping blocks and crank- shaft from time to time and 
the old mixture cleaned off with gasoline. It is necessary 
to maintain a side to side movement of the lapping tool 
in order to have the process affect the whole width of the 
crank-pin equally. The lapping is continued until a 
smooth surface is obtained. If a crank-pin is worn out 
of true to any extent the only method of restoring it is 
to have it ground down to proper circular form by a 
competent mechanic having the necessary machine tools 
to carry on the work accurately. A crank-pin truing 
tool that may be worked by hand is shown at Fig. 187, K. 

After the crank- shaft is trued the next operation is to 
fit it to the main bearings or rather to scrape these mem- 
bers to fit the shaft journal. In order to bring the brasses 
closer together, it may be necessary to remove a little 
metal from the edges of the caps to compensate for the 
lost motion. A very simple way of doing this is shown 
at Fig. 187, D. A piece of medium emery cloth is rested 
on the surface plate and the box or brass is pushed back 
and forth over that member by hand, the amount of pres- 
sure and rapidity of movement being determined by the 
amount of metal it is necessary to remove. This is better 
than filing, because the edges will be flat and there will be 



446 Aviation Engines 

no tendency for the bearing caps to rock when placed 
against the bearing seat. It is important to take enough 
off the edges of the boxes to insure that they will grip 
the crank tightly. The outer diameter must be checked 
"with a pair of calipers during this operation to make sure 
that the surfaces remain parallel. Otherwise, the bearing 
brasses will only grip at one end and with such insuffi- 
cient support they will quickly work loose, both in the 
bearing seat and bearing cap. 

SCRAPING BRASSES TO FIT 

To insure that the bearing brasses will be a good fit 
on the trued-up crank-pins or crank-shaft journals, they 
must be scraped to fit the various crank- shaft journals. 
The process of scraping, while a tedious one, is not diffi- 
cult, requiring only patience and some degree of care to 
do a good job. The surface of the crank-pin is smeared 
with Prussian blue pigment which is spread evenly over 
the entire surface. The bearings are then clamped to- 
gether in the usual manner with the proper bolts, and the 
crank-shaft revolved several times to indicate the high 
spots on the bearing cap. At the start of the process of 
scraping in, the bearing may seat only at a few points as 
shown at Fig. 187, Gr. Continued scraping will bring the 
bearing surface as indicated at H, which is a consider- 
able improvement, while the process may be considered 
complete when the brass indicates a bearing all over as 
at I. The high spots are indicated by blue, as where the 
shaft does not bear on the bearing there is no color. 
The high spots are removed by means of a scraping tool 
of the form shown at Fig. 187, F, which is easily made 
from a worn-out file. These are forged to shape and 
ground hollow as indicated in the section, and are kept 
properly sharpened by frequent rubbing on an ordinary 
oil stone. To scrape properly, the edge of the scraper 
must be very keen. The straight and curved half-round 
scrapers, shown at M and N, are used for bearings. The 



Refitting Engine Bearings 447 

three-cornered scraper, outlined at 0, is also used on 
curved surfaces, and is of value in rounding off the sharp 
corners. The straight or curved half-round type works 
well on soft-bearing metals, such as babbitt, or white brass, 
but on yellow brass or bronze it cuts very slowly, and as 
soon as the edge becomes dull considerable pressure is 
needed to remove any metal, this calling for frequent 
sharpening. 

When correcting errors on flat or curved surfaces by 
hand- scraping, it is desirable, of course, to obtain an 
evenly spotted bearing with as little scraping as possible. 
When the part to be scraped is first applied to the sur- 
face-plate, or to a journal in the case of a bearing, three 
or four "high" spots may be indicated by the marking 
material. The time required to reduce these high spots 
and obtain a bearing that is distributed over the entire 
surface depends largely upon the way the scraping is 
started. If the first bearing marks indicate a decided 
rise in the surface, much time can be saved by scraping 
larger areas than are covered by the bearing marks; this 
is especially true of large shaft and engine bearings, etc. 
An experienced workman will not only remove the heavy 
marks, but also reduce a larger area; then, when the 
bearing is tested again, the marks will generally be dis- 
tributed somewhat. If the heavy marks which usually 
appear at first are simply removed by light scraping, 
these "point bearings" are gradually enlarged, but a 
much longer time will be required to distribute them. 

The number of times the bearing must be applied to 
the journal for testing is important, especially when the 
box or bearing is large and not easily handled. The time 
required to distribute the bearing marks evenly depends 
largely upon one's judgment in "reading" these marks. 
In the early stages of the scraping operation, the marks 
should be used partly as a guide for showing the high 
areas, and instead of merely scraping the marked spot 
the surface surrounding it should also be reduced, unless 
it is evident that the unevenness is local. The idea should 



448 Aviation Engines 

be to obtain first a few large but generally distributed 
marks; then an evenly and finely spotted surface can be 
produced quite easily. 

In fitting brasses when these are of the removable 
type, two methods may be used. The upper half of the 
engine base may be inverted on a suitable bench or stand 
and the boxes fitted by placing the crank-shaft in position, 
clamping down one bearing cap at a time and fitting each 
bearing in succession until they bed equally. From that 
time on the bearings should be fitted at the same time 
so the shaft will be parallel with the bottom of the cylin- 
ders. Considerable time and handling of the heavy crank- 
shaft may be saved if a preliminary fitting of the bearing 
brasses is made by clamping them together with a car- 
penter's wood clamp as shown at Fig. 187, J, and leaving 
the crank-shaft attached to the bench as shown at C. 
The brasses are revolved around the crank- shaft journal 
and are scraped to fit wherever high spots are indicated 
until they begin to seat fairly. "When the brasses assume 
a finished appearance the final scraping should be carried 
on with all bearings in place and revolving the crank- 
shaft to determine the area of the seating. "When the 
brasses are properly fitted they will not only show a full 
bearing surface, but the shaft will not turn unduly hard 
if revolved with a moderate amount of leverage. 

Bearings of white metal or babbitt can be fitted tighter 
than those of bronze, and care must be observed in sup- 
plying lubricant as considerably more than the usual 
amount is needed until the bearings are run in by several 
hours of test block work. Before the scraping process 
is started it is well to chisel an oil groove in the bearing 
as shown at Fig. 187, L. Grooves are very helpful in 
insuring uniform distribution of oil over the entire width 
of bearing and at the same time act as reservoirs to retain 
a supply of oil. The tool used is a round-nosed chisel, 
the effort being made to cut the grooves of uniform 
depth and having smooth sides. Care should be taken 
not to cut the grooves too deeply, as this will seriously 



Fitting Connecting Rods 449 

reduce the strength of the bearing bushing. The shape 
of the groove ordinarily provided is clearly shown at 
Fig. 187, G, and it will be observed that the grooves do 
not extend clear to the edge of the bearing, but stop about 
a quarter of an inch from that point. The hole through 
which the oil is supplied to the bearing is usually drilled 
in such a way that it will communicate with the groove. 

The tool shown at Fig. 187, K, is of recent develop- 
ment, and is known as a "crank-shaft equalizer.' ' This 
is a hand-operated turning tool, carrying cutters which are 
intended to smooth down scored crank-pins without using 
a lathe. The feed may be adjusted by suitable screws 
and the device may be fitted to crank-pins and shaft- 
journals of different diameters by other adjusting screws. 
This device is not hard to operate, being merely clamped 
around the crank-shaft in the same manner as the lapping 
tool previously described, and after it has been properly 
adjusted it is turned around by the levers provided for 
the purpose, the continuous rotary motion removing the 
metal just as a lathe tool would. 

FITTING CONNECTING RODS 

In the marine type rod, which is the form generally 
used in airplane engines, one or two bolts are employed 
at each side and the cap must be removed entirely before 
the bearing can be taken off of the crank-pin. The tight- 
ness of the brasses around the crank-pin can never be 
determined solely by the adjustment of the bolts, as while 
it is important that these should be drawn up as tightly 
as possible, the bearing should fit the shaft without undue 
binding, even if the brasses must be scraped to insure 
a proper fit. As is true of the main bearings, the marine 
form of connecting rod in some engines has a number of 
liners or shims interposed between the top and lower 
portions of the rod end, and these may be reduced in 
number when necessary to bring the brasses closer to- 
gether. The general tendency in airplane engines is to 



450 



Aviation Engines 



eliminate shims in either the main or connecting rod bear- 
ings, and when wear is noticed the boxes or liners are 
removed and new ones supplied. The brasses are held 
in the connecting rod and cap by brass rivets and are 
generally attached in the main bearing by small brass 
machine screws. The form of box generally favored is 
a brass sand casting rich in copper to secure good heat 
conductivity which forms a backing for a thin layer of 
white brass, babbitt or similar anti-friction metal. 

In fitting new brasses there are two conditions to be 
avoided, these being outlined at Fig. 188, B and C. In 




\SmJf^0%$ 



Liners 



Retaining Bolts' 
A 







Retaining Bolts- 
B 



l^^^^^pj 



■Retaining Bolts- 
C 



Fig. 188. — Showing Points to Observe When Fitting Connecting Bod 



the case shown at C the light edges of the bushings are 
in contact, but the connecting rod and its cap do not meet. 
When the retaining nuts are tightened the entire strain 
is taken on the comparatively small area of the edges of 
the bushings which are not strong enough to withstand 
the strains existing and which flatten out quickly, per- 
mitting the bearing to run loose. In the example out- 
lined at B the edges of the brasses do not touch when 
the connecting rod cap is drawn in place. This is not 
good practice, because the brasses soon become loose in 
their retaining member. In the case outlined it is neces- 



Testing Sprung Cam-shaft 451 

sary to file off the faces of the rod and cap until these 
meet, and to insure contact of the edges of the brasses 
as well. In event of the brasses coming together before 
the cap and rod make contact, as shown at C, the bearing 
halves should be reduced at the edges until both the caps 
and brasses meet against each other or the surfaces of 
the liners as shown at A. 



SPRUNG CAM-SHAFT 

If the cam-shaft is sprung or twisted it will alter the 
valve timing to such an extent that the. smoothness of 
operation of the engine will be materially affected. If 
this condition is suspected the cam-shaft may be swung 
on lathe centers and turned to see if it runs out and can 
be straightened in any of the usual form of shaft- straight- 
ening machines. The shaft may be twisted without being 
sprung. This can only be determined by supporting one 
end of the shaft in an index head and the other end on 
a milling machine center. The cams are then checked to 
see that they are separated by the proper degree of angu- 
larity. This process is one that requires a thorough 
knowledge of the valve timing of the engine in question, 
and is best done at the factory where the engine was 
made. The timing gears should also be examined to see 
if the teeth are worn enough so that considerable back 
lash or lost motion exists between them. This is espe- 
cially important where worm or spiral gears are used. 
A worn timing gear not only produces noise, but it will 
cause the time of opening and closing of the engine valves 
to vary materially. 

PRECAUTIONS IN REASSEMBLING PARTS 

When all of the essential components of a power plant 
have been carefully looked over and cleaned and all de- 
fects eliminated, either by adjustment or replacement of 
worn portions, the motor should be reassembled, taking 



452 Aviation Engines 

care to have the parts occupy just the same relative posi- 
tions they did before the motor was dismantled. As each 
part is added to the assemblage care should be taken to 
insure adequate lubrication of all new points of bearing 
by squirting liberal quantities of cylinder oil upon them 
with a hand oil can or syringe provided for the purpose. 
In adjusting the crank-shaft bearings, tighten them one 
at a time and revolve the shafts each time one of the 
bearing caps is set up to insure that the newly adjusted 
bearing does not have undue friction. All retaining keys 
and pins must be positively placed and it is good practice 
to cover such a part with lubricant before replacing it 
because it will not only drive in easier, but the part may 
be removed more easily if necessary at some future time. 
If not oiled, rust collects around it. 

"When a piece is held by more than one bolt or screw, 
especially if it is a casting of brittle material such as 
cast iron or aluminum, the fastening bolts should be tight- 
ened uniformly. If one bolt is tightened more than the 
rest it is liable to spring the casting enough to break it. 
Spring washers, rheck nuts, split pins or other locking 
means should always be provided, especially on parts 
which are in motion or subjected to heavy loads. 

Before placing the cylinder over the piston it is im- 
perative that the slots in the piston rings are spaced 
equidistant and that the piston is copiously oiled before 
the cylinder is slipped over it. When reassembling the 
inlet and exhaust manifolds it is well to use only perfect 
packings or gaskets and to avoid the use of those that 
seem to have hardened up or flattened out too much in 
service. If it is necessary to use new gaskets it is im- 
perative to employ these at all joints on a manifold, be- 
cause if old and new gaskets are used together the new 
ones are apt to keep the manifold from bedding properly 
upon the used ones. It is well to coat the threads of all 
bolts and screws subjected to heat, such as cylinder head 
and exhaust manifold retaining bolts, with a mixture of 
graphite and oil. Those that enter the water jacket should 



Reassembling Parts 453 

be covered with white or red lead or pipe thread com- 
pound. Gaskets will hold better if coated with shellac 
before the manifold or other parts are placed over them. 
The shellac fills any irregularities in the joint and assists 
materially in preventing leakage after the joint is made 
up and the coating has a chance to set. 

Before assembling on the shaft, it is necessary to fit 
the bearings by scraping, the same instructions given for 
restoring the contour of the main bearings applying just 
as well in this case. It is apparent that if the crank-pins 
are not round no amount of scraping will insure a true 
bearing. A point to observe is to make sure that the 
heads of the bolts are imbedded solidly in their proper 
position, and that they are not raised by any burrs or 
particles of dirt under the head which will flatten out 
after the engine has been run for a time and allow the 
bolts to slack off. Similarly, care should be taken that 
there is no foreign matter under the brasses and the 
box in which they seat. To guard against this the bolts 
should be struck with a hammer several times after they 
are tightened up, and the connecting rod can be hit 
sharply several times under the cap with a wooden mallet 
or lead hammer. It is important to pin the brasses in 
place to prevent movement, as lubrication may be inter- 
fered with if the bushing turns round and breaks the cor- 
rect register between the oil hole in the cap and brasses. 

Care should be taken in screwing on the retaining nuts 
to insure that they will remain in place and not slack off. 
Spring washers should not be used on either connecting 
rod ends or main bearing nuts, because these sometimes 
snap in two pieces and leave the nut slack. The best 
method of locking is to use well-fitting split pins and 
castellated nuts. 

TESTING BEARING PARALLELISM 

It is not possible to give other than general directions 
regarding the proper degree of tightening for a con- 
necting rod bearing, but as a guide to correct adjustment 



454 Aviation Engines 

it may be said that if the connecting rod cap is tightened 
sufficiently so the connecting rod will just about fall over 
from a vertical position due to the piston weight when 
the bolts are fully tightened up, the adjustment will be 
nearly correct. As previously stated, babbitt or white 
metal bearings can be set up more tightly than bronze, 
as the metal is softer and any high spots will soon be 
leveled down with the running of the engine. It is im- 
portant that care be taken to preserve parallelism of 
the wrist-pins and crank-shafts while scraping in bear- 
ings. This can be determined in two ways. That shown 
at Fig. 189, A, is used when the parts are not in the 
engine assembly and when the connecting rod bearing is 
being fitted to a mandrel or arbor the same size as the 
crank-pin. The arbor, which is finished very smooth and 
of uniform diameter, is placed in two V blocks, which in 
turn are supported by a level surface plate. An ad- 
justable height gauge may be tried, first at one side of 
the wrist-pin which is placed at the upper end of the 
connecting rod, then at the other, and any variation will 
be easily determined by the degree of tilting of the. rod. 
This test may be made with the wrist-pin alone, or if 
the piston is in place, a straight edge or spirit level may 
be employed. The spirit level will readily show any in- 
clination while the straight edge is used in connection 
with the height gauge as indicated. Of course, the sur- 
face plate must be absolutely level when tests are made. 
When the connecting rods are being fitted with the 
crank- shaft in place in crank-case, and that member se- 
cured in the frame, a steel square may be used as it is 
reasonable to assume that the wrist-pin, and consequently 
the piston it carries, should observe a true relation with 
the top of the engine base. If the piston side is at right 
angles with the top of the engine base it is reasonable 
to assume that the wrist-pin and crank-pin are parallel. 
If the piston is canted to one side or the other, it will 
indicate that the brasses have been scraped tapering, 
which would mean considerable heating and undue fric- 



Testing Bearing Parallelism 



4*55 



tion if the piston is installed in the cylinder on account 
of the pressure against one portion of the cylinder wall. 
If the degree of canting is not too great, the connecting 
rods may be sprung very slightly to straighten up the 



Height Gage. 



c »UU 



Mandrel- 



Mandrel*, 
V-Block 



E^k 




j? 



y Straight Edge ' 



-Piston 



-Connecting Rod 

,- V-Block 



Surface Plate- 



Square^ 



Connecting /fo^.CTp 




Piston 



OP .,- Qflh 



,'• Cylinder Bed 



H 



Crank Case 



„ M \tj 



f 



uy yu 




_jJUSfl 



Front Bearing Center Bearing \ End Bearing 



Fig. 189. — Methods of Testing to Insure Parallelism of Bearings After 

Fitting. 

piston, but this is a makeshift that is not advised. The 
height gauge method shown above may be used instead 
of the steel square, if desired, because the top of the 
crank-case is planed or milled true and should be parallel 
with the center line of the crank-shaft. 



4*56 Aviation Engines 

CAM-SHAFTS AND TIMING GEARS 

Knocking sounds are also evident if the cam-shaft is 
loose in its bearings, and also if the cams or timing 
gears are loose on the shaft. The cam-shaft is usually 
supported by solid bearings of the removable bushing 
type, having no compensation for depreciation. If these 
bearings wear the only remedy is replacement with new 
ones. In the older makes of cars it was general practice 
to machine the cams separately and to secure these to the 
cam-shaft by means of taper pins or keys. These mem- 
bers sometimes loosened and caused noise. In the event 
of the cams being loose, care should be taken to use new 
keys or taper pins, as the case may be. If the fastening 
used was a pin, the hole through the cam-shaft will 
invariably be slightly oval from wear. In order to insure 
a tight job, the holes in cam and shaft must be reamed 
with the next larger size of standard taper reamer and 
a larger pin driven in. Another point to watch is the 
method of retaining the cam-shaft gear in place. On 
some engines the gear is fastened to a flange on the 
cam-shaft by retaining screws. These are not apt to 
become loose, but where reliance is placed on a key the 
cam-shaft gear may often be loose on its supporting 
member. The only remedy is to enlarge the key slot 
in both gear and shaft and to fit a larger retaining key. 



CHAPTER XII 

Aviation Engine Types — Division in Classes — Anzani Engines — Canton 
and Unne Engine — Construction of Gnome Engines— "Monosou- 
pape" Gnome — .German "Gnome" Type — Le Rhone Engine — 
Renault Air-Cooled Engine — Simplex Model "A" Hispana-Suiza 
— Curtiss Aviation Motors — Thomas-Morse Model 88 Engine — 
Duesenberg Engine — Aeromarine Six-Cylinder — Wisconsin Avia- 
tion Engines — Hall-Scott Engines — Mercedes Motor — Benz Motor 
— Austro-Daimler — Sunbeam-Coatalen. 



AVIATION ENGINE TYPES 

Inasmuch as numerous forms of airplane engines have 
been devised, it would require a volume of considerable 
size to describe even the most important developments 
of recent years. As considerable explanatory matter has 
been given in preceding chapters and the principles in- 
volved in internal combustion engine operation consid- 
ered in detail, a relatively brief review of the features 
of some of the most successful airplane motors should 
suffice to give the reader a complete enough understand- 
ing of the art so all types of engines can be readily 
recognized and the advantages and disadvantages of each 
type understood, as well as defining the constructional 
features enough so the methods of locating and repair- 
ing the common engine and auxiliary system troubles 
will be fully grasped. 

Aviation engines can be divided into three main 
classes. One of the earliest attempts to devise distinctive 
power plant designs for aircraft involved the construc- 
tion of engines utilizing a radial arrangement of the 
cylinders or a star-wise disposition. Among the engines 
of this class may be mentioned the Anzani, E. E. P. and 
the Salmson or Canton and Unne forms. The two former 
are air-cooled, the latter design is water-cooled. Engines 

457 



_ 



458 Aviation Engines 

of this type have been built in cylinder numbers ranging 
from three to twenty. While the simple forms were 
popular in the early days of aviation engine develop- 
ment, they have been succeeded by the more conventional 
arrangements which now form the largest class. The 
reason for the adoption of a star-wise arrangement of 
cylinders has been previously considered. Smoothness 
of running can only be obtained by using a considerable 
number of cylinders. The fundamental reason for the 
adoption of the star-wise disposition is that a better dis- 
• tribution of stress is obtained by having all of the pistons 
acting on the same crank-pin so that the crank-throw and 
pin are continuously under maximum stress. Some diffi- 
culty has been experienced in lubricating the lower cylin- 
ders in some forms of six cylinder, rotary crank, radial 
engines but these have been largely overcome so they are 
not as serious in practice as a theoretical consideration 
would indicate. 

Another class of engines developed to meet aviation 
requirements is a complete departure from the preceding 
class, though when the engines are at rest, it is difficult 
to differentiate between them. This class includes en- 
gines having a star-wise disposition of the cylinders but 
the cylinders themselves and the crank-case rotate and 
the crank- shaft remains stationary. The important rotary 
engines are the Gnome, the Le Ehone and the Clerget. 
By far the most important classification is that includ- 
ing engines which retain the approved design of the 
types of power plants that have been so widely utilized 
in automobiles and which have but slight modifications 
to increase reliability and mechanical strength and pro- 
duce a reduction in weight. This class includes the 
vertical engines such as the Duesenberg and Hall-Scott 
four-cylinder; the Wisconsin, Aeromarine, Mercedes, 
Benz, and Hall-Scott six-cylinder vertical engines and 
the numerous eight- and twelve-cylinder Vee designs such 
as the Curtiss, Eenault, Thomas-Morse, Sturtevant, Sun- 
beam, and others. 



Anzani Air-Cooled Engines 459 

AXZAXI ENGINES 

The attention of the mechanical world was first di- 
rected to the great possibilities of mechanical flight when 
Bleriot crossed the English Channel in July, 1909, in a 
monoplane of his own design and construction, having 
the power furnished by a small three-cylinder air-cooled 
engine rated at about 24 horse-power and having cylin- 
ders 4.13 inches bore and 5.12 inches stroke, stated to 
develop the power at about 1600 R.P.M. and weighing 145 
pounds. The arrangement of this early Anzani engine is 
shown at Fig. 190, and it will be apparent that in the 
main, the lines worked out in motorcycle practice were 
followed to a large extent. The crank-case was of the 
usual vertically divided pattern, the cylinders and heads 
being cast in one piece and held to the crank-case by 
stud bolts passing through substantial flanges at the 
cylinder base. In order to utilize but a single crank-pin 
for the three cylinders it was necessary to use two forked 
rods and one rod of the conventional type. The arrange- 
ment shown at Fig. 190, called for the use of counter- 
balanced flywheels which were built up in connection 
with shafts and a crank-pin to form what corresponds to 
the usual crank-shaft assembly. 

The inlet valves were of the automatic type so that a 
very simple valve mechanism consisting only of the ex- 
haust valve push rods was provided. One of the diffi- 
culties of this arrangement of cylinders was that the 
impulses are not evenly spaced. For instance, in the 
forms where the cylinders were placed 60 degrees apart 
the space between the firing of the first cylinder and that 
next in order was 120 degrees crank-shaft rotation, after 
which there was an interval of 300 degrees before the 
last cylinder to fire delivered its power stroke. In order 
to increase the power given by the simple three-cylinder 
air-cooled engine a six-cylinder water-cooled type, as 
shown at Figs. 191 and 192, was devised. This was prac- 
tically the same in action as the three-cylinder except 



460 



Aviation Engines 





Fig. 190a. — Illustrations Depicting Wrong and Right Methods of "Swing- 
ing the Stick" to Start Airplane Engine. At Top, Poor Position to 
Get Full Throw and Get Out of the Way. Below, Correct Position 
to Get Quick Turn Over of Crank-Shaft and Spring Away from 
Propeller. 

461 



462 



Aviation Engines 



that a double throw crank-shaft was used and while the 
explosions were not evenly spaced the number of explo- 
sions obtained resulted in fairly uniform application of 
power. 

The latest design of three-cylinder Anzani engine, 
which is used to some extent for school machines, is 
shown at Fig. 193. In this, the three-cylinders are sym- 







Fig. 191. — The Anzani Six-Cylinder Water-Cooled Aviation Engine. 



metrically arranged about the crank-case or 120 degrees 
apart. The balance is greatly improved by this arrange- 
ment and the power strokes occur at equal intervals of 
240 degrees of crank- shaft rotation. This method of con- 
struction is known as the Y design. By grouping two of 
these engines together, as outlined at Fig. 194, which 
gives an internal view, and at Fig. 195, which shows the 
sectional view, and using the ordinary form of double 
throw crank-shaft with crank-pins separated by 180 de- 
grees, a six-cylinder radial engine is produced which runs 



Anzani Aviation Engines 



463 



very quietly and furnishes a steady output of power. 
The peculiarity of the construction of this engine is in 
the method of grouping the connecting rod about the 
common crank-pin without using forked rods or the 
"Mother rod" system employed in the Gnome engines. 
In the Anzani the method followed is to provide each 



,Cooling Water 
Outlets— 



.-Water Jacket 



Water 
Ouilet 




Connecting- 
Rods. 



Crank-Shaft" 



Crank Case--' 



K Exhaust 
Valve 



'Cylinder 



Flywheel 



Fig. 192.— Sectional View of Anzani Six-Cylinder Water-Cooled Aviation 

Engine. 

connecting rod big end with a shoe which consists of a 
portion of a hollow cylinder held against the crank-pin 
by split clamping rings. The dimensions of these shoes 
are so proportioned that the two adjacent connecting rods 
of a group of three will not come into contact even when 
the connecting rods are at the minimum relative angle. 
The three shoes of each group rest upon a bronze sleeve 
which is in halves and which surrounds the crank-pin 



464 



Aviation Engines 



and rotates relatively to it once in each crank-shaft revo- 
lution. The collars, which are of tough bronze, resist the 
inertia forces while the direct pressure of the explosions 
is transmitted directly to the crank-pin bushing by the 
shoes at the big end of the connecting rod. The same 



Va I v e 
Operating Rod 



Intake Pipe ,___ 



Wt^.-'Cy Under No J 



<-- 'Cylinder hold 
down Bolts 




, Spark Plug 



Cylinder No. 3-'' 

Carburetor 



v.G.HAGSTROM N.Y. 



Fig. 193.— Three-Cylinder Anzani Air-Cooled Y-Form Engine. 



method of construction, modified to some extent, is used 
in the LeKhone rotary cylinder engine. 

Both cylinders and pistons of the Anzani engines are 
of cast iron, the cylinders being provided with a liberal 
number of cooling flanges which are cast integrally. A 
series of auxiliary exhaust ports is drilled near the base 



Anzani Engine Construction 



465 



of each cylinder so that a portion of the exhaust gases 
will flow out of the cylinder when the piston reaches the 
end of its power stroke. This reduces the temperature 
of the gases passing around the exhaust valves and pre- 



Exhaust 
Elbow 



Exhaust-^ /Valve 

.Spark Plug 



■Induction Pipe 




Valve Rocker- 



K -Valve Lift Rod 



Carburetor 



A.G.HAGSTROM N.Y. 



Pig. 194.— Anzani Fixed Crank-Case Engine of the Six-Cylinder Form 
Utilizes Air Cooling Successfully. 



vents warping of these members. Another distinctive 
feature of this engine design is the method of attaching 
the Zenith carburetor to an annular chamber surrounding 
the rear portion of the crank-case from which the intake 
pipes leading to the intake valves radiate. The magneto 



466 



Aviation Engines 



is the usual six-cylinder form having the armature geared 
to revolve at one and one-half times crank- shaft speed. 

The Anzani aviation engines are also made in ten- 
and twenty-cylinder forms as shown at Fig. 196. It will 



Propel/en 



Exhaust Valve Rocker 



■Exhaust Valve. Push Rod 




' Magneto 
Magneto Drive Gear 

^-Intake Gas Passage 

..---- Carburetor 

~~ Primary /fir Intake. 



~-EueI Pipe 
77/r Cooled Cylinder 



Fig. 195. — Sectional View Showing Internal Parts of Six-Cylinder Anzani 
Engine, with Starwise Disposition of Cylinders. 



rr 



468 



Aviation Engines 



be apparent that in the ten-cylinder form explosions will 
occur every 72 degrees of crank-shaft rotation, while in 
the twenty-cylinder, 200 horse-power engine at any in- 




Fig. 197. — Application of R. E. P. Five-Cylinder Fan-Shape Air-Cooled 
Motor to Early Monoplane. 



stant five of the cylinders are always working and ex- 
plosions are occurring every 36 degrees of crank-shaft 
rotation. On the twenty-cylinder engine, two carburetors 



Canton and Unne Engine 469 

are used and two magnetos, which are driven at two and 
one-half times crank-shaft speed. The general cylinder 
and valve construction is practically the same, as in the 
simpler engines. 

canton and unne engine 

This engine, which has been devised specially for 
aviation service, is generally known as the "Salmson" 
and is manufactured in both France and Great Britain. 
It is a nine-cylinder water-cooled radial engine, the nine- 
cylinders being symmetrically disposed around the crank- 
shaft while the nine connecting rods all operate on a 
comman crank-pin in somewhat the same manner as the 
rods in the Gnome motor. The crank-shaft of the Salm- 
son engine is not a fixed one and inasmuch as the cylin- 
ders do not rotate about the crank-shaft it is necessary 
for that member to revolve as in the conventional engine. 
The stout hollow steel crank-shaft is in two pieces and 
has a single throw. The crank-shaft is built up some- 
what the same as that of the Gnome engine. Ball bear- 
ings are used throughout this engine as will be evident 
by inspecting the sectional view given at Fig. 199. The 
nine steel connecting rods are machined all over and are 
fitted at each end with bronze bushings, the distance 
between the bearing centers being about 3.2c times crank 
length. The method of connecting up the rods to the 
crank-pin is one of the characteristic features of this 
design. No " mother" rod as supplied in the Gnome 
engine is used in this type inasmuch as the steel cage or 
connecting rod carrier is fitted with symmetrically dis- 
posed big end retaining pins. Inasmuch as the carrier 
is mounted on ball bearings some means must be pro- 
vided of regulating the motion of the carrier as if no 
means were provided the resulting motion of the pistons 
would be irregular. 

The method by which the piston strokes are made to 
occur at precise intervals involves a somewhat lengthy 
and detailed technical explanation. It is sufficient to say 



470 



Aviation Engines 



that an epicyclic train of gears, one of which is rigidly 
attached to the crank-case so it cannot rotate is used, 
while other gears make a connection between the fixed 
gear and with another gear which is exactly the same 







Fig. 198. — The Canton and Unne Nine-Cylinder Water-Cooled Radial 

Engine. 



size as the fixed gear'attached to the crank-case" and which 
is formed integrally with the connecting rod carrier. The 
action of the gearing is such that the cage carrying the 
big end retaining pins does not rotate independently of 



Canton and Unne Engine 



471 



the crank- shaft, though, of course, the crank-shaft or 
rather crank-pin bearings must turn inside of the big 
end carrier cage. 

Cylinders of this engine are of nickel steel machined 
all over and carry water-jackets of spun copper which 
are attached to the cylinders by brazing. The water 



Rocker Lever — ''"J^ 
Valve Rocker Support- 
Valve Stem 



.Torsion Type^ 
I Valve Spring 




Non-Rotating 
Crank Case 



-.Equalizing 
Gear 
Train 



tfi'-Fixed 
Equalizing 
Gear 



'■Ro ta ry 
Crank Shaft 



? "--■•-:-:..: . $Ur I'^Radial Ball 
; 7-Cams^^%_Ji Bearings 

"• Cam Assembly Drive Gear 
Cam Drive Gear 



Crankshaft Bearings 



Fig. 199. — Sectional View Showing Construction of Canton and Unne 
Water-Cooled Radial Cylinder Engine. 



jackets are corrugated to permit the cylinder to expand 
freely. The ignition is similar to that of the fixed crank 
rotating cylinder engine. An ordinary magneto of the 
two spark type driven at 1% times crank- shaft speed is 
sufficient to ignite the seven-cylinder form, while in the 



472 Aviation Engines 

nine-cylinder engines the ignition magneto is of the 
" shield' ' type giving four sparks per revolution. The 
magneto is driven at 1% times crank-shaft speed. Nickel 
steel valves are used and are carried in castings or cages 
which screw into bosses in the cylinder head. Each 
valve is cam operated through a tappet, push rod and 
rocker arm, seven cams being used on a seven-cylinder 
engine and nine cams on the nine-cylinder. One cam 
serves to open both valves as in its rotation it lifts the 
tappets in succession and so operates the exhaust and 
inlet valves respectively. This method of operation in- 
volves the same period of intake and exhaust. In nor- 
mal engine practice the inlet valve opens 12 degrees 
late and closes 20 degrees late. The exhaust opens 
45 degrees early and closes 6 degrees late. This means 
about 188 degrees in the case of inlet valve and 231 de- 
grees crank-shaft travel for exhaust valves. In the 
Salmson engine, the exhaust closes and the inlet opens at 
the outer dead center and the exhaust opens and the inlet 
closes at about the inner dead center. This engine is 
also made in a fourteen-cylinder 200 B. H. P. design 
which is composed of two groups of seven-cylinders, and 
it has been made in an eighteen-cylinder design of 600 
horse-power. The nine-cylinder 130 horse-power has a 
cylinder bore of 4.73 inches and a stroke of 5.52 inches. 
Its normal speed of rotation is 1250 K. P. M. Owing to 
the radial arrangement of the cylinders, the weight is but 
4% pounds per B. H. P. 



construction or eakly gnome motor 

It cannot be denied that for a time one of the most 
widely used of aeroplane motors was the seven-cylinder 
revolving air-cooled Gnome, made in France. For a total 
weight of 167 pounds this motor developed 45 to 47 horse- 
power at 1,000 revolutions, being equal to 3.35 pounds 
per horse-power, and has proved its reliability by securing 
many long-distance and endurance records. The same 




473 



474 Aviation Engines 

engineers have produced a nine-cylinder and by combi- 
ning two single engines a fourteen-cylinder revolving 
Gnome, having a nominal rating of 100 horse-power, with 
which world's speed records were broken. A still more 
powerful engine has been made with eighteen-cylinders. 
The nine-cylinder "monosoupape" delivers 100 horse- 
power at 1200 E. P. M., the engine of double that number 
of cylinders is rated at about 180 horse-power. 

Except in the number of cylinders and a few mechani- 
cal details the fourteen-cylinder motor is identical with 
the seven-cylinder one; fully three-quarters of the parts 
used by the assemblers would do just as well for one 
motor as for the other. Owing to the greater power de- 
mands of the modern airplane the smaller sizes of Gnome 
engines are not used as much as they were except for 
school machines. There is very little in this motor that 
is common to the standard type of vertical motorcar 
engine. The cylinders are mounted radially round a cir- 
cular crank-case; the crank-shaft is fixed, and the entire 
mass of cylinders and crank-case revolves around it as 
outlined at Fig. 200. The explosive mixture and the 
lubricating oil are admitted through the fixed hollow 
crank-shaft, passed into the explosion chamber through 
an automatic intake valve in the piston head in the early 
pattern, and the spent gases exhausted through a me- 
chanically operated valve in the cylinder head. The 
course of the gases is practically a radial one. A pecu- 
liarity of the construction of the motor is that nickel steel 
is used throughout. Aluminum is employed for the two 
oil pump housings; the single compression ring known 
as the ' ' obdurator ' ' for each piston is made of brass; 
there are three or four brass bushes; gun metal is em- 
ployed for certain pins — the rest is machined out of 
chrome nickel steel. The crank-case is practically a steel 
hoop, the depth depending on whether it has to receive 
seven- or f ourteen-cylinders ; it has seven or fourteen 
holes bored as illustrated on its circumference. When 
fourteen or eighteen cylinders are used the holes are 



Gnome Engine Details 475 

bored in two distinct planes, and offset in relation one to 
the other. 

The cylinders of the small engine which have a bore 
of 4%o inches and a stroke of 4%o inches, are machined 
out of the solid bar of steel nntil the thickness of the walls 
is only 1.5 millimeters — .05905 inch, or practically % 6 inch. 
Each one has twenty- two fins which gradually taper down 
as the region of greatest pressure is departed from. In 
addition to carrying away heat, the fins assist in strength- 
ening the walls of the cylinder. The barrel of the cylin- 
der is slipped into the hole bored for it on the circum- 
ference of the crank-case and secured by a locking member 
in the nature of a stout compression ring, sprung onto a 
groove on the base of the cylinder within the crank cham- 
ber. On each lateral face of the crank chamber are seven 
holes, drilled right through the chamber parallel with the 
crank-shaft. Each one of these holes receives a stout 
locking-pin of such a diameter that it presses against 
the split rings of two adjacent cylinders; in addition 
each cylinder is fitted with a key- way. This construction 
is not always followed, some of the early Gnome engines 
using the same system of cylinder retention as used on 
the latest "monosoupape" pattern. 

The exhaust valve is mounted in the cylinder head, 
Fig. 201, its seating being screwed in by means of a 
special box spanner. On the fourteen-cylinder model the 
valve is operated directly by an overhead rocker arm 
with a gun metal rocker at its extremity coming in con- 
tact with the extremity of the valve stem. As in standard 
motor car practice, the valve is opened under the lift of 
the vertical push rod, actuated by the cam. The distinc- 
tive feature is the use of a four-blade leaf spring with 
a forked end encircling the valve stems and pressing 
against a collar on its extremity. On the seven-cylinder 
model the movement is reversed, the valve being opened 
on the downward pull of the push rod, this lifting the 
outer extremity of the main rocker arm, which tips a 
secondary and smaller rocker arm in direct contact with 



476 



Aviation Engines 



the extremity of the valve stem. The springs are the 
same in each case. The two types are compared at A 
and B, Fig. 202. 



Exhaust Valve Spring^ 



--Valve Depressing 
Rocker 



..Exhaust Valve 
Cage 



^Cooling 
' Flanges 




.---**-** "Piston 

Rings 



-Cylinder 



^ Valve Actuating Push Rod 



Fig. 201. — Sectional View of Early Type Gnome Cylinder and Piston 
Showing Construction and Application of Inlet and Exhaust Valves. 

The pistons, like the cylinders, are machined out of 
the solid bar of nickel steel, and have a portion of their 
wall cut away, so that the two adjacent ones will not 
come together at the extremity of their stroke. The head 





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-£§ 



o 
o < 

2 



<i> 

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477 



478 Aviation Engines 

of the piston is slightly reduced in diameter and is pro- 
vided with a groove into which is fitted a very light 
L-section brass split ring; back of this ring and carried 
within the groove is sprung a light steel compression 
ring, serving to keep the brass ring in expansion. As 
already mentioned, the intake valves are automatic, and 
are mounted in the head of the piston as outlined at Fig. 
202, C. The valve seating is in halves, the lower portion 
being made to receive the wrist-pin and connecting rod, 
and the upper portion, carrying the valve, being screwed 
into it. The spring is composed of four flat blades, with 
the hollowed stem of the automatic valve passing through 
their center and their two extremities attached to small 
levers calculated to give balance against centrifugal force. 
The springs are naturally within the piston, and are lubri- 
cated by splash from the crank chamber. They are of 
a delicate construction, for it is necessary that they shall 
be accurately balanced so as to have no tendency to fly 
open under the action of centrifugal force. The intake 
valve is withdrawn by the use of special tools through the 
cylinder head, the exhaust valve being first dismounted. 
The fourteen-cylinder motor shown at Fig. 203, has a 
two-throw crank-shaft with the throws placed at 180 de- 
grees, each one receiving seven connecting rods. The 
parts are the same as for the seven-cylinder motor, the 
larger one consisting of two groups placed side by side. 
For each group of seven-cylinders there is one main con- 
necting rod, together with six auxiliary rods. The main 
connecting rod, which, like the others, is of H section, has 
machined with it two L-section rings bored with six holes 
— 511^ degrees apart to take the six other connecting 
rods. The cage of the main connecting rod carries two 
ball races, one on either side, fitting onto the crank-pin 
and receiving the thrust of the seven connecting rods. 
The auxiliary connecting rods are secured in position in 
each case by a hollow steel pin passing through the two 
rings. It is evident that there is a slightly greater angu- 
larity for the six shorter rods, known as auxiliary con- 



Gnome Engine Details 



479 




ja/iaaojj Jo 



a 
W 

o 



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u 
o 
o 

E 

B 

o 
o 

H 

M 

-d 

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•ft 
o 

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B 

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aw/7 tel^d 



480 Aviation Engines 

necting rods, than for the longer main rods; this does not 
appear to have any influence on the running of the motor. 

Coming to the manner in which the earliest design ex- 
haust valves are operated on the old style motor, this at 
first sight appears to be one of the most complicated 
parts of the motor, probably because it is one in which 
standard practice is most widely departed from. Within 
the cylindrical casing bolted to the rear face of the crank- 
case are seven, thin flat-faced steel rings, forming female 
cams. Across a diameter of each ring is a pair of pro- 
jecting rods fitting in brass guides and having their 
extremities terminating in a knuckle eye receiving the 
adjustable push rods operating the overhead rocker arms 
of the exhaust valve. The guides are not all in the same 
plane, the difference being equal to the thickness of the 
steel rings, the total thickness being practically 2 inches. 
Within the female cams is a group of seven male cams 
of the same total thickness as the former and rotating 
within them. As the boss of the male cam comes into 
contact with the flattened portion of the ring forming 
the female cam, the arm is pushed outward and the ex- 
haust valve opened through the medium of the push-rod 
and overhead rocker. This construction was afterwards 
changed to seven male cams and simple valve operating 
plunger and roller cam followers as shown at Fig. 204. 

On the face of the crank-case of the four teen-cylinder 
motor opposite to the valve mechanism is a bolted-on end 
plate, carrying a pinion for driving the two magnetos 
and the two oil pumps, and having bolted to it the dis- 
tributor for the high-tension current. Each group of 
seven-cylinders has its own magneto and lubricating 
pump. The two magnetos and the two pumps are mounted 
on the fixed platform carrying the stationary crank-shaft, 
being driven by the pinion on the revolving crank cham- 
ber. The magnetos are geared up in the proportion of 
4 to 7. Mounted on the end plate back of the driving 
pinion "are" the two high-tension distributor plates, each 
one with seven brass segments let into it and connection 



Gnome Engine Details 



481 



made to the plugs by means of plain brass wire. The 
wire passes through a hole in the plug and is then 
wrapped round itself, giving a loose connection. 



Revolving C ^"V 

Planetary Drive 

Pinions, eear > 



Non- 
Rota five 
Timing 
Gear , 



Valve- Actuating Tube 

.-Valve Plunger Guide 
.••Valve Plunger 




Revolving Planetary 
Pinions 



Cam Case Flange 



Fig. 204. — Cam and Cam-Gear Case of the Gnome Seven-Cylinder 
Revolving Engine. 



m 



482 



Aviation Engines 



A good many people doubtless wonder why rotary en- 
gines are usually provided with an odd number of cylin- 
ders in preference to an even number. It is a matter of 
even torque, as can easily be understood from the accom- 
panying diagram. Fig. 205, A, represents a six-cylinder 
rotary engine, the radial lines indicating the cylinders. 
It is possible to fire the charges in two ways, firstly, in 
rotation, 1, 2, 3, 4, 5, 6, thus having six impulses in one 
revolution and none in the next; or alternately, 1, 3, 5, 2, 
4, 6, in which case the engine will have turned through 



6<^ 




. 2 

NA 6 


' ^ 


7\ a 






5 










*t 


A 


5 « 


B 



Fig. 205. — Diagrams Showing Why An Odd Number of Cylinders is Best 
for Rotary Cylinder Motors. 

an equal number of degrees between impulses 1 and 3, 
and 3 and 5, but a greater number between 5 and 2, even 
again between 2 and 4, 4 and 6, and a less number be- 
tween 6 and 1, as will be clearly seen on reference to the 
diagram. Turning to Fig. 205, B, which represents a 
seven-cylinder engine. If the cylinders fire alternately 
it is obvious that the engine turns through an equal 
number of degrees between each impulse, thus, 1, 3, 5, 7, 
2, 4, 6, 1, 3, etc. Thus supposing the engine to be revolv- 
ing, the explosion takes place as each alternate cylinder 
passes, for instance, the point 1 on the diagram, and the 
ignition is actually operated in this way by a single 
contact. 



Gnome Engine Details 



483 



The crank-shaft of the Gnome, as already explained, 
is fixed and hollow. For the seven- and nine-cylinder 
motors it has a single throw, and for the fourteen- and 
eighteen-cylinder models has two throws at 180 degrees. 
It is of the built-up type, this being necessary on account 



/Throttle Lever 



.Crank- Shaft End 



&///////////> 



Gas to "* 
Crank-Case 
Interior - 



Y///// S. 



Y/////U 



Coupling 
Nut 




Tig. 206.— Simple Carburetor Used On Early Gnome Engines Attached 
to Fixed Crank-Shaft End. 



of the distinctive mounting of the connecting rods. The 
carburetor shown at Fig. 206 is mounted at one end of 
the stationary crank-shaft, and the mixture is drawn in 
through a valve in the piston as already explained. There 
is neither float chamber nor jet. In many of the tests 
made at the factory it is said the motor will run with the 
extremity of the gasoline pipe pushed into the hollow 



484 



Aviation Engines 



crank-shaft, speed being regulated entirely by increasing 
or decreasing the flow through the shut-off valve in the 
base of the tank. Even under these conditions the motor 
has been throttled down to run at 350 revolutions with- 
out misfiring. Its normal speed is 1,000 to 1,200 revolu- 
tions a minute. Castor oil is used for lubricating the 
engine, the oil being injected into the hollow crank-shaft 



Ball Bearings ^ 



Pump Drive Sear 



Worm 



Worm Shaft-' 

Driving Worm'' 
Pumping Cam 1 ' 




•Valve 
Plunger 



v Plunger Return 
Springs 



Fig. 207. — Sectional Views of the Gnome Oil Pump. 

through slight-feed fittings by a mechanically operated 
pump which is clearly shown in sectional diagrams at 
Fig. 207. 

The Gnome is a considerable consumer of lubricant, 
the makers' estimate being 7 pints an hour for the 100 
horse-power motor; but in practice this is largely ex- 
ceeded. The gasoline consumption is given as 300 to 350 
grammes per horse-power. The total weight of the four- 
teen-cylinder motor is 220 pounds without fuel or lubri- 



Gnome Engine Details 



485 



eating oil. Its full power is developed at 1,200 revolu- 
tions, and at this speed about 9 horse-power is lost in 
overcoming air resistance to cylinder rotation. 

While the Gnome engine has many advantages, on the 
other hand, the head resistance offered by a motor of this 



Current Supply Brush* 



QZ. 




■Secondary Wire to Plug 



<— Ignition 
Current 
Supply Wire 




^ Spark Plug 



/Pole Pieces, 



C 



Breaker 
Points. 



^ 




"Magneto 
Collector Ring 



^Double wound 
Armature 



M a gnet"'' 




Fig. 208. — Simplified Diagram Showing Gnome Motor Magneto Ignition 

System. 



type is considerable; there is a large waste of lubricating 
oil due to the centrifugal force which tends to throw the 
oil awav from the cylinders; the gyroscopic effect of 
the rotary motor is detrimental to the best working of the 
aeroplane, and moreover it requires about seven per cent, 
of the total power developed by the motor to drive the 
revolving cylinders around the shaft. Of necessity, the 



486 Aviation Engines 

compression of this type of motor is rather low, and an 
additional disadvantage manifests itself in the fact that 
there is as yet no satisfactory way of muffling the rotary 
type of motor. 

GNOME "mONOSOUPAPe" TYPE 

The latest type of Gnome engine is known as the 
"monosoupape" type because but one valve is used in 
the cylinder head, the inlet valve in the piston being dis- 
pensed with on account of the trouble caused by that 
member on earlier engines. The construction of this 
latest type follows the lines established in the earlier 
designs to some extent and it differs only in the method 
of charging. The very rich mixture of gas and air is 
forced into the crank-case through the jet inside the 
crank-shaft, and enters the cylinder when the piston is 
at its lowest position, through the half-round openings 
in the guiding flange and the small holes or ports ma- 
chined in the cylinder and clearly shown at Fig. 210. 
The returning piston covers the port, and the gas is com- 
pressed and fired in the usual way. The exhaust is 
through a large single valve in the cylinder head, which 
gives rise to the name "monosoupape," or single-valve 
motor, and this valve also remains open a portion of the 
intake stroke to admit air into the cylinder and dilute 
the rich gas forced in from the crank-case interior. 
Aviators who have used the early form of Gnome say 
that the inlet valve in the piston type was prone to catch 
on fire if any valve defect materialized, but the "monosou- 
pape" pattern is said to be nearly free of this danger. 
The bore of the 100 horse-power nine-cylinder engine is 
110 mm., the piston stroke 150 mm. Extremely careful 
machine work and fitting is necessary. In many parts, 
tolerances of less than .0004" (four ten thousandths of 
an inch) are all that are allowed. This is about one- 
sixth the thickness of the average human hair, and in 
other parts the size must be absolutely standard, no 
appreciable variation being allowable. The manufacture 



Gnome Monosoupape Engine 



487 



of this engine establishes new mechanical standards of 
engine production in this country. Much machine work 
is needed in producing the finished components from the 
bar and forging. 

The cylinders, for example, are machined from 6 inch 
solid steel bars, which are sawed into blanks 11 inches 









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Fig. 209. — The G. V. Gnome "Monosoupape" Nine-Cylinder Rotary Engine 
Mounted on Testing Stand. 



in length and weighing about 97 pounds. The first opera- 
tion is to drill a 2Y 1G inch hole through the center of the 
block. A heavy-duty drilling machine performs this 



488 



Aviation Engines 




Ghiome Monosoupape Engine 



489 



work, then the block goes to the lathe for further opera- 
tions. Fig. 211 shows six stages of the progress of a 
cylinder, a few of the intermediate steps being omitted. 







B i 

"88 Si 








W .■' ,, 










-3"-ir. T - 



Fig. 211.— How a Gnome Cylinder is Reduced from Solid Chunk of Steel 
Weighing 97 Pounds to Finished Cylinder Weighing 5y 2 Pounds. 

These give, however, a good idea of the work done. The 
turning of the gills, or cooling flanges, is a difficult propo- 
sition, owing to the depth of the cut and the thin metal 
that forms the gills. This operation requires the utmost 
care of tools and the use of a good lubricant to prevent 



490 Aviation Engines 

the metal from tearing as the tools approach their full 
depth. These gills are only 0.6 mm., or 0.0237 in., thick 
at the top, tapering to a thickness of J..4 mm. (0.0553 in.) 
at the base, and are 16 mm. (0.632 in.) deep. When the 
machine work is completed the cylinder weighs but 5% 
pounds. 



GNOME FUEL SYSTEM, IGNITION AND LUBRICATION 

The following description of the fuel supply, ignition 
and oiling of the "monosoupape," or single valve Gnome, 
is taken from "The Automobile. ' ' 

Gasoline is fed to the engine by means of air pressure 
at 5 pounds per sq. in., which is produced by the air 
pump on the engine clearly shown at Fig. 210. A pres- 
sure gauge convenient to the operator indicates this pres- 
sure, and a valve enables the operator to control it. No 
carburetor is used. The gasoline flows from the tank 
through a shut- off valve near the operator and through 
a tube leading through the hollow crank-shaft to a spray 
nozzle located in the crank-case. There is no throttle 
valve, and as each cylinder always receives the same 
amount of air as long as the atmospheric pressure is the 
same, the output cannot be varied by reducing the fuel 
supply, except within narrow limits. A fuel capacity of 
65 gallons is provided. The fuel consumption is at the 
rate of 12 TJ. S. gallons per hour. 

The high-tension magnetos, with double cam or two 
break per revolution interrupter, is located on the thrust 
plate in an inverted position, and is driven at such a 
speed as to produce nine sparks for every two revolu- 
tions; that is, at 2*4 times engine speed. A Splitdorf 
magneto is fitted. There is no distributor on the mag- 
neto. The high-tension collector brush of the magneto 
is connected to a distributor brush holder carried in the 
bearer plate of the engine. The brush in this brush 
holder is pressed against a distributor ring of insulating 
material molded in position in the web of a gear wheel 



Gnome Monosoup ape Engine 491 

keyed to the thrust plate, which gear serves-; also for 
starting the engine by hand. Molded in this ring of in- 
sulating material are nine brass contact sectors, connect- 
ing with contact screws at the back side of the gear, 
from which bare wires connect to the spark-plugs. The 
distributor revolves at engine speed, instead of St half 
engine speed as on ordinary engines, and the distributor 
brush is brought into electrical connection with each 





— -^--^— ^^ 


4flu 


sJm' 


dim* 


# 1m 


^■^!db_'- ** 


' *~* *—"-~ *"^ 



Tig. 212. — The Gnome Engine Cam-Gear Case, a Fine Example of Accurate 

Machine Work. 

spark-plug every time the piston in the cylinder in which 
this spark-plug is located approaches the outer dead 
center. However, on the exhaust stroke no spark is being 
generated in the magneto, hence none is produced at the 
spark-plug. 

Ordinarily the engine is started by turning on the 
propeller, but for emergency purposes as in seaplanes or 
for a quick "get away" if landing inadvertently in 
enemy territory, a hand starting crank is provided. This 
is supported in bearings secured to the pressed steel 
carriers of the engine and is provided with a universal 



492 



Aviation Engines 



joint between the two supports so as to prevent binding 
of the crank in the bearings due to possible distortion 
of the supports. The gear on this starting crank and the 
one on the thrust plate with which it meshes are cut 




Fig. 213. — G. V. Gnome "Monosoupape,," with Cam-Case Cover Removed to 
Show Cams and Valve-Operating Plungers with Roller Cam Followers. 

with helical teeth of such hand that the starting pinion 
is thrown out of mesh as soon as the engine picks up its 
cycle. A coiled spring surrounds part of the shaft of the 
starting crank and holds it out of gear when not in use. 
Lubricating oil is carried in a tank of 25 gallon ca- 
pacity, and if this tank has to be placed in a low position 



German Gnome Type Engine 493 

it is connected with the air-pressure line, so that the 
suction of the oil pump is not depended upon to get the 
oil to the pump. From the bottom of the oil tank a pipe 
leads to the pump inlet. There are two outlets from the 
pump, each entering the hollow crank-shaft, and there is 
a branch from each outlet pipe to a circulation indicator 
convenient to the operator. One of the oil leads feeds 
to the housing in the thrust plate containing the two rear 
ball bearings, and the other lead feeds through the crank- 
pin to the cams, as already explained. 

Owing to the effect of centrifugal force and the fact 
that the oil is not used over again, the oil consumption 
of a revolving cylinder engine is considerably higher than 
that of a stationary cylinder engine. Fuel consumption 
is also somewhat higher, and for this reason the revolv- 
ing cylinder engine is not so well suited for types of air- 
planes designed for long trips, as the increased weight 
of supplies required for such trips, as compared with 
stationary cylinder type motors, more than offsets the 
high weight efficiency of the engine itself. But for short 
trips, and especially where high speed is required, as in 
single seated scout and battle planes or "avious de 
chasse," as the French say, the revolving cylinder engine 
has the advantage. The oil consumption of the Gnome 
engine is as high as 2.4 gallon per hour. Castor oil is 
used for lubrication because it is not cut by the gasoline 
mist present in the engine interior as an oil of mineral 
derivation would be. 



GERMAN " GNOME " TYPE ENGINE 

A German adaptation of the Gnome design is shown 
at Fig. 214. This is known as the Bayerischen Motoren 
Gesellshaft engine and the type shown is an early design 
rated at 50 horse-power. The bore is 110 mm., the stroke 
is 120 mm., and it is designed to run at a speed of 1,200 
E. P. M. It is somewhat similar in design to the early 
Gnome "valve-in-piston" design except that two valves 



494 



Aviation Engines 



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Le Rhone Rotary Motor 495 

are carried in the piston top instead of one. The valve 
operating arrangement is different also, as a single four 
point cam is nsed to operate the seven exhaust valves. 
It is driven by epicyclic gearing, the cam being driven by 
an internal gear machined integrally with it, the cam 
being turned at % times the engine speed. Another 
feature is the method of holding the cylinders on the 
crank-case. The cylinder is provided with a flange that 
registers with a corresponding member of the same diam- 
eter on the crank-case. A U section, split clamping ring 
is bolted in place as shown,, this holding both flanges 
firmly together and keeping the cylinder firmly seated 
against the crank-case flange. The "monosoupape" type 
has also been copied and has received some application 
in Germany, but the most successful German airplanes 
are powered with six-cylinder vertical engines such as 
the Benz and Mercedes. 



THE LE RHONE MOTOR 

The Le Ehone motor is a radial revolving cylinder 
engine that has many of the principles which are incor- 
porated in the Gnome but which are considered to be an 
improvement by many foreign aviators. Instead of having 
but one valve in the cylinder head, as the latest type 
"monosoupape" Gnome has, the Le Rhone has two valves, 
one for intake and one for exhaust in each cylinder. By 
an ingenious rocker arm and tappet rod arrangement 
it is possible to operate both valves with a single push 
rod. Inlet pipes communicate with the crank-case at one 
end and direct the fresh gas to the inlet valve cage at the 
other. Another peculiarity in the design is the method 
of holding the cylinders in place. Instead of having a 
vertically divided crank-case as the Gnome engine has 
and clamping both valves of the case around the cylin- 
ders, the crank-case of the Le Rhone engine is in the 
form of a cylinder having nine bosses provided with 
threaded openings into which the cylinders are screwed. 



496 



Aviation Engines 



A thread is provided at the base of each cylinder and 
when the cylinder has been screwed down the proper 
amount it is prevented from further rotation about its 
own axis by a substantial lock nut which screws down 




Fig. 215. — Nine-Cylinder Revolving Le Rhone Type Aviation Engine. 

against the threaded boss on the crank-case. The ex- 
ternal appearance of the Le Ehone type motor is clearly 
shown at Fig. 215, while the general features of con- 
struction are clearly outlined in the sectional views given 
at Figs. 216 and 217. 




497 



498 



Aviation Engines 



The two main peculiarities of this motor are the 
method of valve actuation by two large cams and the 
distinctive crank-shaft and connecting rod big end con- 
struction. The connecting rods are provided with "feet" 
or shoes on the end which fit into grooves lined with 
bearing metal which are machined into crank discs 




^—Ball Bearing RockerShaft 

Valve Operating Rod 

• Operating Rod Plunger 

.-Ignition Distributor 



■Current Supply Brush 



si i , )h l 



Propeller Shaft 



Rotary Crank Case 



Fixed 
Crank-Shaft'' 



'•Anchorage Plates*'' 
*■*- Ball Bearing 



Fig. 217. — Side Sectional View of Le Rhone Aviation Engine. 

revolving on ball bearings and which are held together so 
that the connecting rod big ends are sandwiched between 
them by clamping screws. This construction is a modifi- 
cation of that used on the Anzani six-cylinder radial 
engine. There are three grooves machined in each crank 
disc and three connecting rod big ends run in each pair 
of grooves. The details of this construction can be readily 
ascertained by reference to explanatory diagrams at 
Figs. 218 and 219, A. Three of the rods which work 



Le Rhone Rotary Motor 



499 



in the groove nearest the crank-pin are provided with 
short shoes as shown at Fig. 219, B. The short shoes 
are used on the rods employed in cylinders number 1, 
4, and 7. The set of connecting rods that work in the 
central grooves are provided with medium-length shoes 



Exhaust 
Valve 



,.' Piston 

r .*'A ir Co o I in g Fla nges 




Threads to 
hold Cylinder 



Crank Case--' 



Connecting 
Rod 



Connecting Rod 
and Crank Shaft 
Assembly 



Valve Lift Rods 



Fig. 218.— View Showing Le Rhone Valve Action and Connecting Rod 
Big End Arrangement. 

and actuate the pistons in cylinders numbers 3, 6, and 9. 
The three rods that work in the outside grooves have still 
longer shoes and are employed in cylinders numbers 2, 
-5, and 8. The peculiar profile of the inlet and exhaust 
<?am plates are shown at C, Fig. 219, while the construc- 
tion of the wrist-pin, wrist-pin bushing and piston are 
-clearly outlined at the sectional view at E. The method 



500 



Aviation Engines 



of valve actuation is clearly outlined at Fig. 220, which 
shows an end section through the cam case and also 
a partial side elevation showing one of the valve operating 
levers which is fulcrumed at a central point and which 




« 



Short- Rod End Feet Medium Rod End Feet 



0n#l-4-7 



B 



1 



on*3-6-9 



Lonq Rod End Feet 

on*2-5-8 

Arrangement of Curved Bearingson 

Connecting Rod Ends 



Diagram Showing Connecting 
Rod Assembly 



Piston . 



Wrist Pin-' 




Into ke Cam 



Fig. 219. — Diagrams Showing Important Components of Le Rhone Motor. 



has a roller at one end bearing on one cam while the 
roller or cam follower at the other end bears on the other 
cam. The valve rocker arm actuating rod is, of course, 
operated by this simple lever and is attached to it in 
such a way that it can be pulled down to depress the 
inlet valve and pushed up to open the exhaust valve. 



Le Rhone Engine Details 



501 



A carburetor of peculiar construction is employed in 
the Le Bhone engine, this being a very simple type as 
outlined at Fig. 221. It is attached to the threaded end 
of the hollow crank-shaft by a right and left coupling. 



Rocker Shaft Actuator.. 
Rocker'Shaft Bearing' 

Vaive Rocker- ' 

Exhaust Valve-. ^ 



rCam Drive Gear Internal 




Valve Actuating Rod- 



Air Cooled 

Cylinder-*:- 



Fulcrum .„_ 



Valve Operating... 
Lever 



Fixed Cam / 

.CrankShaft Follower-- 



H 



HFI 




I ''Cam Plate Supporting 
Ball Bearings 



'Internal Pinion 
'Internal dear 



Fig. 220. — How the Cams of the Le Rhone Motor Can Operate Two Valves 
with a Single Push Rod. 



502 



Aviation Engines 



The fuel is pumped to the spray nozzle, the opening in 
which is controlled by a fuel regulating needle having 
a long taper which is lifted out of the jet opening when 
the air-regulating slide is moved. The amount of fuel 
supplied the carburetor is controlled by a special needle 
valve fitting which combines a filter screen and which is 
shown at B. In regulating the speed of the Le Ehone 



Slide Operating 
Link 



Regulating Slide- 
Air Screen - 



'Air Entrance 



■Link 

■Valve Stem 
■.Stuffing Box 
---Packing 




Fig. 221. — The Le Rhone Carburetor at A and Fuel Supply Regulating 

Device at B. 



engine, there are two possible means of controlling the 
mixture, one by altering the position of the air-regulating 
slide, which also works the metering needle in the jet, and 
the other by controlling the amount of fuel supplied to 
the spray nozzle through the special fitting provided for 
that purpose. 

In considering the action of this engine one can refer 
to Fig. 222. The crank 0. M. is fixed, while the cylinders 
can turn about the crank-shaft center and the piston 



Le Rhone Engine Action 



503 



turns around the crank-pin M, because of the eccentricity 
of the centers of rotation the piston will reciprocate in 
the cylinders. This distance is at its maximum when 
the cylinder is above and at a minimum when it is 
above M, and the difference between these two positions 
is equal to the stroke, which is twice the distance of the 
crank-throw 0, M. The explosion pressure resolves itself 
into the force F exerted along the line of the connecting 
rod A, M, and also into a force N, which tends to make 



Crank Pin --., 
Center 



^ 
Crank Shaft-' / 
Center 



\ 




Firing Order* 
1-3-5-1-9-2-4-6-8 



Fig. 222. — Diagrams Showing Le Rhone Motor Action and Firing Order. 



the cylinders rotate around point in the direction of 
the arrow. An odd number of cylinders acting on one 
crank-pin is desirable to secure equally spaced explosions, 
as the basic action is the same as the Gnome engine. 

The magneto is driven by a gear having 36 teeth at- 
tached to crank-case which meshes with 16-tooth pinion 
on armature. The magneto turns at 2.25 times crank- 
case speed. Two cams, one for inlet, one for exhaust, 
are mounted on a carrying member and act on nine 
rocker arms which are capable of giving a push-and-pull 



504 



Aviation Engines 



motion to the valve-actuating rocker-operating rods. A 
gear driven by the crank-case meshes with a larger mem- 
ber having internal teeth carried by the cam carrier. 
Each cam has five profiles and is mounted in staggered 



Top Dead 
A Center 




Bottom Dead 
Center 



Fig. 223. — Diagram Showing Positions of Piston in Le Rhone Rotary 

Cylinder Motor. 



relation to the other. These give the nine fulcrumed 
levers the proper motion to open the inlet and exhaust 
valves at the proper time. The cams are driven at 
4 %o or %o of the motor speed. The cylinder dimensions 
and timing follows; the weight can be approximated by 
figuring 3 pounds per horse-power. 



Renault Air-Cooled Vee 'Engine 



505 



80 H. P 105 M/M bore 4.20" bore. 

140 M/M stroke 5.60" stroke. 

110 H. P 112 M/M bore 4.48" bore. 

170 M/M stroke 6.80" stroke. 



18°"^ 
°l 



35' 



Timing — Intake valve opening-, lag- 18°~ 

Intake valve closing, lag 35° 

Exhaust valve opening, lead 55° >110 H. P. 45° ^80 H. P. 

Exhaust'valve closing, lag 5° 5° I 

Ignition time advance 26°J 26° J 



THE RENAULT AIR-COOLED VEE ENGINE 

Air-cooled stationary engines are rarely used in air- 
planes, but the Eenault Freres of France have for several 
years manufactured a complete series of such engines of 
the general design shown at Fig. 225, ranging from a 




Openinq of Inlet Valve 
A 





Inlet Valve Clos/nq 
B 



I an iti on Point 
C 



Fi ring Order 
1-3-5-7-9-Z-4-6-8 



Opening of Exhaust 



--8 



Exhaust Valve Closinq 
E 



Fig. 224. — Diagrams Showing Valve Timing of Le Rhone Aviation Engine. 



506 



Aviation Engines 



low-powered one developed eight or nine years ago and 
rated at 40 and 50 horse-power, to later eight-cylinder 



-~*/7/r Stove 



fc; 3<- -J-' Exhaust 
= '' Pipes 



/ Supporting Tube 



Blower Casing 




J ,-Biower 
Casing 



^Supporting Tubes 



Fig. 225. — Diagrams Showing How Cylinder Cooling is Effected in 
Renault Vee Engines. 

models rated at 70 horse-power and a twelve-cylinder, or 
twin six, rated at 90 horse-power. The cylinders are of 
cast iron and are furnished with numerous cooling ribs 



Renault Air-Cooled Vee Engine 



507 



which are cast integrally. The cylinder heads are sepa- 
rate castings and are attached to the cylinder as in early 
motorcycle engine practice, and serve to hold the cylinder 
in place on the alnminnm alloy crank-case by a cruciform 
yoke and four long hold-down bolts (Fig. 226). The 



,- Exhaust Valve Operating Rod 

■Spark Plugs- 



Exhaust Valve, 



Cylinder 



Hold down Bolts—--:" 




Supporting Tube-' 

Breather- 



Crank Shaft - 
Oil Pump Drive Rod — 

Oil Strainer | 

Oil Pump 



Fig. 226. — End Sectional View of Renault Air-Cooled Aviation Engine. 

pistons are of cast steel and utilize piston rings of cast 
iron. The valves are situated on the inner side of the 
cylinder head, the arrangement being unconventional in 
that the exhaust valves are placed above the inlet. The 
inlet valves seat in an extension of the combustion head 
and are actuated by direct push rod and cam in the usual 
manner while an overhead gear in which rockers are oper- 



508 Aviation Engines 

ated by push rods is needed to actuate the exhaust valves. 
The valve action is clearly shown in Figs. 226 and 227. 
The air stream by which the cylinders are cooled is pro- 
duced by a centrifugal or blower type fan of relatively 
large diameter which is mounted on the end of a crank- 
shaft and the air blast is delivered from this blower into 
an enclosed space between the cylinder from which it 
escapes only after passing over the cooling fins. In 
spite of the fact that considerable prejudice exists against 
air-cooling fixed cylinder engines, the Eenault has given 
very good service in both England and France. 

As will be seen by the sectional view at Fig. 227, the 
steel crank-shaft is carried in a combination of plain 
bearings inside the crank-case and by ball bearings at the 
ends. Owing to air cooling, special precautions are taken 
With the lubrication system, though the lubrication is not 
forced or under high pressure. An oil pump of the gear- 
wheel type delivers oil from the sump at the bottom of the 
crank-case to a chamber above, from which the oil flows 
by gravity along suitable channels to the various main 
bearings. It flows from the bearings into hollow rings 
fastened to the crank-webs, and the oil thrown from the 
whirling connecting rod big ends bathes the internal 
parts in an oil mist. In the eight-cylinder designs igni- 
tion is effected by a magneto giving four sparks per revo- 
lution and is accordingly driven at engine speed. In the 
twelve-cylinder machine two magnetos of the ordinary 
revolving armature or two-spark type, each supplying 
six cylinders, are fitted as outlined at Fig. 228. The 
carburetor is a float feed form. Warm air is supplied 
for Winter and damp weather by air pipes surrounding 
the exhaust pipes. The normal speed of the Renault 
engine is 1,800 R. P. M., but as the propeller is mounted 
upon an extension of the cam-shaft the normal propeller 
speed is but half that of the engine, which makes it pos- 
sible to use a propeller of large diameter and high effi- 
ciency. Owing to the air cooling, but low compression 
may be used, this being about 60 pounds per square inch, 




509 



510 



Aviation Engines 



which, of course, lowers the mean effective pressure and 
makes the engine less efficient than water-cooled forms 
where it is possible to use compression pressure of 100 



Distributor..^ 



/Magnetos- 
Magneto, 



Oil Filler and 

Breather Pipe 



/Distributor 



/Magneto 
Drive Gear 




Engine < \ 
Supporting"' 
Tube 



Fig. 228.— End View of Renault Twelve-Cylinder Engine Crank-Case, 
Showing Magneto Mounting. 



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511 



512 Aviation Engines 

or more pounds per square inch. The 70 horse-power 
engine has cylinders with a bore of 3.78 inches and a 
stroke of 5.52 inches. Its weight is given as 396 pounds, 
when in running order, which figures 5.7 pounds per 
horse-power. The same cylinder size is used on the 
twelve-cylinder 100 horse-power and the stroke is the 
same. This engine in running order weighs 638 pounds, 
which figures approximately 6.4 pounds per B. H. P. 



The Model A is of the water-cooled four-cycle Vee 
type, with eight cylinders, 4.7245 inch bore by 5.1182 inch 
stroke, piston displacement 718 cubic inches. At sea-level 
it develops 150 horse-power at 1,450 E. P. M. It can 
be run successfully at much higher speeds, depending 
on propeller design and gearing, developing proportion- 
ately increased power. The weight, including carburetor, 
two magnetos, propeller hub, starting magneto and crank, 
but without radiator, water or oil or exhaust pipes, is 
445 pounds. Average fuel consumption is .5 pound per 
horse-power hour and the oil consumption at 1,450 R. P. 
M. is three quarts per hour. The external appearance is 
shown at Fig. 230. 

Four cylinders are contained in each block, which is 
of built-up construction; the water jackets and valve 
ports are cast aluminum and the individual cylinders 
heat-treated steel forgings threaded into the bored holes 
of the aluminum castings. Each block after assembly is 
given a number of protective coats of enamel, both inside 
and out, baked on. Coats on the inside are applied 
under pressure. The pistons are aluminum castings, 
ribbed. Connecting rods are tubular, of the forked type. 
One rod bears directly on the crank-pin; the other rod 
has a bearing on the outside of the one first mentioned. 

The crank-shaft is of the five-bearing type, very short, 
stiff in design, bored for lightness and for the oiling 
system. The crank-shaft extension is tapered for the 



His pano- Suiza Engine 



513 



French standard propeller hub, which is keyed and 
locked to the shaft. This makes possible instant change 
of propellers. The case is in two halves divided on the 
center line of the crank-shaft, the bearings being fitted 
between the npper and lower sections. The lower half 
is deep, providing a large oil reservoir and stiffening 
"the engine. The upper half is simple and provides mag- 
neto supports on extension ledges of the two main faces. 
The valves are of large diameter with hollow stems, 





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Tig. 230. — The Simplex Model A Hispano-Suiza Aviation Engine, a Very 

Successful Form. 

working in cast iron bushings. They are directly operated 
by a single hollow cam-shaft located over the valves. The 
cam-shafts are driven from the crank-shaft by vertical 
shafts and bevel gears. The cam-shafts, cams and heads 
of the valve stems are all enclosed in oil-tight removable 
housings of cast aluminum. 

Oiling is by a positive pressure system. The oil is 
taken through a filter and steel tubes cast in the case 
to main bearings, through crank-shaft to crank-pins. 
The fourth main bearing is also provided with an oil 
lead from the system and through tubes running up the 
end of each cylinder block, oil is provided for the cam- 



514 Aviation Engines 

shafts, cams and bearings. The surplus oil escapes 
through the end of the cam-shaft where the driving gears 
are mounted, and with the oil that has gathered in the 
top casing, descends through the drive shaft and gears 
to the sump. 

Ignition is by two eight-cylinder magnetos firing two 
spark-plugs per cylinder. The magnetos are driven 
from each of the two vertical shafts by small bevel 
pinions meshing in bevel gears. The carburetor is 
mounted between the two cylinder blocks and feeds the 
two blocks through aluminum manifolds which are partly 
water- jacketed. The engine can be equipped with a 
geared hand crank- starting device. 

STURTEVAXT MODEL 5a 140 HORSE-POWER ENGINE 

These motors are of the eight-cylinder "V" type, four- 
stroke cycle, water-cooled, having a bore of 4 inches and 
a stroke of 5% inches, equivalent to 102 mm. x 140 mm. 
The normal operating speed of the crank-shaft is 2,000 
K. P. M. The propeller shaft is driven through reducing 
gears which can be furnished in different gear ratios. 
The standard ratio is 5.3, allowing a propeller speed of 
1,200 E. P. M. 

The construction of the motor is such as to permit 
of the application of a direct drive. The change from the 
direct drive to gear drive, or vice versa, can be accom- 
plished in approximately one hour. 

The cylinders are cast in pairs from an aluminum 
alloy and are provided with steel sleeves, carefully fitted 
into each cylinder. A perfect contact is secured between 
cylinder and sleeve; at the same time a sleeve can be 
replaced without injury to the cylinder proper. No dif- 
ficulties due to expansion occur on account of the rapid 
transmission of heat and the fact that the sleeve is al- 
ways at higher temperature than the cylinder. A moulded 
copper asbestos gasket is placed between the cylinder 
and the head, permitting the cooling water to circulate 



Sturtevant Model 5 A Engine 515 

freely and at the same time insuring a tight joint. The 
cylinder heads are cast in pairs from an aluminum alloy 
and contain ample water passages for circulation of 
cooling water over the entire head. Trouble due to hot 
valves is thereby eliminated, a most important consid- 
eration in the operation of an aeroplane motor. The 
water jacket of the head corresponds to the water jacket 
of the cylinders and large openings in both allow the 
unobstructed circulation of the cooling water. The cylin- 
der heads and cylinders are both held to the base by six 
long bolts. The valves are located in the cylinder heads 
and are mechanically operated. The valves and valve 
springs are especially accessible and of such size as to 
permit high volumetric efficiency. The valves are con- 
structed of hardened tungsten steel, the heads and stems 
being made from, one piece. The valve rocker arms 
located on the top of the cylinder are provided with 
adjusting screws. A check nut enables the adjusting 
screw to be securely locked in position, once the correct 
clearance has been determined. The rocker arm bearings 
are adequately lubricated by a compression grease cup. 
Cam-rollers are interposed between the cams and the 
push rods in order to reduce the side thrust on the push 
rods. 

A system of double springs is employed which greatly 
reduces the stress on each spring and insures utmost 
reliability. A spring of extremely large diameter returns 
the valve; a second spring located at the cylinder base 
handles the push rod linkage. These springs, which 
operate under low stress, are made from the best of steel 
and are given a special double heat treatment. The 
pistons are made from a special aluminum alloy; are 
deeply ribbed in the head for cooling and strength and 
provided with two piston rings. These pistons are ex- 
ceedingly light weight in order to minimize vibration and 
prevent wear on the bearings. The piston pin is made of 
chrome nickel steel, bored hollow and hardened. It is 
allowed to turn, both in piston and connecting rod. The 



516 Aviation Engines 

piston rings are of special design, developed after years 
of experimenting in aeronautical engines. 

The connecting rods are of "H" section, machined 
all over from forgings of a special air-hardening chrome 
nickel steel which, after being heat treated has a tensile 
strength of 280,000 ponnds per square inch. They are 
consequently very strong and yet unusually light, and 
being machined all over are of absolutely uniform section, 
which gives as nearly perfect balance as can be obtained. 
The big ends are lined with white metal and the small 
ends are bushed with phosphor bronze. The connecting 
rods are all alike and take their bearings side by side on 
the crank-pin, the cylinders being offset to permit of 
this arrangement. The crank-shaft is machined from 
the highest grade chrome nickel steel, heat treated in 
order to obtain the best properties . of this material. 
It is 214 inches in diameter (57 mm.) and bored hollow 
throughout, insuring maximum strength with minimum 
weight. It is carried in three large, bronze-backed white 
metal bearings. A new method of producing these bear- 
ings insures a perfect bond between the two metals and 
eliminates breakage. 

The base is cast from an aluminum alloy. Great 
strength and rigidity is combined with light weight. The 
sides extend considerably below the center line of the 
crank-shaft, providing an extremely deep section. At 
all highly stressed points, deep ribs are provided to dis- 
tribute the load evenly and eliminate bending. The lower 
half of the base is of cast aluminum alloy of extreme 
lightness. This collects the lubricating oil and acts as 
a small reservoir for same. An oil-filtering screen of 
large area covers the entire surface of the sump. The 
propeller shaft is carried on two large annular ball bear- 
ings driven from the crank- shaft by hardened chrome 
nickel steel spur gears. These gears are contained within 
an oil-tight casing integral with the base on the oppo- 
site end from the timing gears. A ball -thrust bearing 
is provided on the propeller shaft to take the thrust of 



Sturtevant Model 5 A Engine 517 

a propeller or tractor, as the case may be. In case of the 
direct drive a stub shaft is fastened direct to the crank- 
shaft and is fitted with a donble thrust bearing. 

The cam-shaft is contained within the upper half of 
the base between the two groups of cylinders, and is 
supported in six bronze bearings. It is bored hollow 
throughout and the cams are formed integral with the 
shaft and ground to the proper shape and finish. An 
important development in the shape of cams has resulted 
in a maintained increase of power at high speeds. The 
gears operating the cam-shaft, magneto, oil and water 
pumps are contained within an oil-tight casing and oper- 
ate in a bath of oil. 

Lubrication is of the complete forced circulating sys- 
tem, the oil being supplied to every bearing under high 
pressure by a rotary pump of large capacity. This is 
operated by gears from the crank-shaft. The oil passages 
from the pump to the main bearings are cast integral 
with the base, the hollow crank-shaft forming a passage 
through the connecting rod bearings and the hollow cam- 
shaft distributing the oil to the cam-shaft bearings. The 
entire surface of the ]ower half of the base is covered 
with a fine mesh screen through which the oil passes 
before reaching the pump. Approximately one gallon of 
oil is contained within the base and this is continually 
circulated through an external tank by a secondary pump 
operated by an eccentric on the cam-shaft. This also 
draws fresh oil from the external tank which can be made 
of any desired capacity. 

SPECIFICATIONS MODEL 5a TYPE 8 

Horse-power rating, 140 at 2,000 R. P. M. 

Bore, 4 inches = 102 mm. 

Stroke, 5% inches = 140 mm. 

Number of cylinders, 8. 

Arrangement of cylinders, "V." 

Cooling, water. Circulation by centrifugal pump. 



518 Aviation Engines 

Cycle, four stroke. 

Ignition (double), 2 Bosch or Splitdorf magnetos. 

Carburetor, Zenith duplex. Water jacket manifold. 

Oiling system, complete forced. Circulating gear pump. 

Normal crank-shaft speed, 2,000 R. P. M. 

Propeller shaft, % crank-shaft speed at normal, 1,200 

R. P. M. 
Stated power at 30" barometer, 140 B. H. P. 
Stated weight with all accessories but without water, 

gasoline or oil, 514 pounds = 234 kilos. 
Weight per B. II. P., 3.7 pounds = 1.68 kilos. 
Stated weight with all accessories with water, 550 pounds 

= 250 kilos. 
Weight per B. H. P. with water, 3.95 pounds = 1.79 

kilos. 

HE CURTISS AVIATION MOTORS 

The Curtiss OX motor has eight cylinders, 4-inch 
bore, 5-inch stroke, delivers 90 horse-power at 1,400 turns, 
and the weight turns out at 4.17 pounds per horse-power. 
This motor has cast iron cylinders with monel metal 
jackets, overhead inclined valves operated by means of 
two rocker arms, push-and-pull rods from the central 
cam-shaft located in the crank-case. The cam and push 
rod design is extremely ingenious and the whole valve 
construction turns out very light. This motor is an 
evolution from the early Curtiss type motor which was 
used by Glenn Curtiss when he won the Gordon Bennett 
Cup at Rheims. A slightly larger edition of this type 
motor is the OXX 5, as shown at Figs. 231 and 232, 
which has cylinders 4*4 inches by 5 inches, delivers 100 
horse-power at 1,400 turns and has the same fuel and 
oil consumption as the OX type motor, namely, .60 pound 
of fuel per brake horse-power hour and .03 pound of 
lubricating oil per brake horse-power hour. 

The Curtiss Company have developed in the last 
two years a larger-sized motor now known as the V-2, 
which was originally rated at 160 horse-power and which 



Curtiss Aviation Motors 



519 



has since been refined and improved so that the motor 
gives 220 horse-power at 1,400 turns, with a fuel con- 
sumption of 5 %oo of a pound per brake horse-power hour 
and an oil consumption of .02 of a pound per brake 
horse-power hour. This larger motor has a weight of 3.45 
pounds per horse-power and is now said to be giving 



Maqneto 



Valve Ac+iori\ 




Ware r 
PumD 



Water-'"' 
Jacketed 

lntakePfpe f jj|Slg ; ;*' V^ Carburetor 

Y 



Oil Gauge 



Fig. 231.— The Curtiss OXX5 Aviation Engine is an Eight-Cylinder Type 
Largely Used on Training Machines. 



very satisfactory service. The V-2 motor has drawn 
steel cylinders, with a bore of 5 inches and a stroke of 
7 inches, with a steel water jacket top and a monel metal 
cylindrical jacket, both of which are brazed on to the 
cylinder barrel itself. Both these motors use side by 
side connecting rods and fully forced lubrication. The 
cam-shafts act as a gallery from which the oil is dis- 
tributed to the cam-shaft bearings, the main crank-shaft 



520 



Aviation Engines 



hearings, and the gearing. Here again we find extremely 
short rods, which, as before mentioned, enables the height 
and the consequent weight of construction to be very 
much reduced. For ordinary flying at altitudes of 5,000 



Propeller 
Hub 




Viewed' "from 

,-,-Bo+to.m 



Tig. 232.— Top and Bottom Views of the Curtiss OXX5 100 Horse-Power 

Aviation Engine. 



to 6,000 feet, the motors are sent out with an aluminum 
liner, bolted between the cylinder and the crank-case in 
order to give a compression ratio which does not result 
in pre-ignition at a low altitude. For high flying, how- 
ever, these aluminum liners are taken out and the com- 



Thomas Morse Engine 521 

pression volume is decreased to about 18.6 per cent, of 
the total volume. 

The Curtiss Aeroplane Company announces that it has 
recently built, and is offering, a twelve-cylinder 5"x7" 
motor, which was designed for aeronautical uses primar- 
ily. This engine is rated at 250 horse-power, but it is 
claimed to develop 300 at 1,400 E. P. M. Weights— Motor, 
1,125 pounds; radiator, 120 pounds; cooling water, 100 
pounds ; propeller, 95 pounds. 

Gasoline Consumption per Horse-power Hour, %<> 
pounds. 

Oil Consumption per Hour at Maximum Speed — 2 
pints. 

Installation Dimensions — Overall length, 84% inches; 
overall width, 34% inches; overall depth, 40 inches; 
width at bed, 30% inches; height from bed, 21% inches; 
depth from bed, 18% inches. 

THOMAS-MORSE MODEL 88 ENGINE 

The Thomas-Morse Aircraft Corporation of Ithaca, 
N. Y., has produced a new engine, Model 88, bearing a 
close resemblance to the earlier model. The main features 
of that model have been retained; in fact, many parts 
are interchangeable in the two engines. Supported by 
the great development in the wide use of aluminum, the 
Thomas engineers have adopted this material for cylinder 
construction, which adoption forms the main departure 
from previous accepted design. 

The marked tendency to-day toward a higher speed 
of rotation has been conclusively justified, in the opinion 
of the Thomas engineers, by the continued reliable per- 
formance of engines with crank-shafts operating at speeds 
near 2,000 revolutions per minute, driving the propeller 
through suitable gearing at the most efficient speed. 
High speed demands that the closest attention be paid 
to the design of reciprocating and rotating parts and 
their adjacent units. Steel of the highest obtainable 



522 Aviation Engines 

tensile strength must be used for connecting rods and 
piston pins, that they may be light and yet retain a 
sufficient factor of safety. Piston design is likewise 
subjected to the same strict scrutiny. At the present 
day, aluminum alloy pistons operate so satisfactorily 
that they may be said to have come to stay. 

The statement often made in the past, that the gear- 
ing down of an engine costs more in the weight of re- 
duction gears and propeller shaft than is warranted by 
the increase in horse-power, is seldom heard to-day. 

The mean effective pressure remaining the same, the 
brake horse-power of any engine increases as the speed. 
That is, an engine delivering 100 brake horse-power at 
1,500 revolutions per minute will show 133 brake horse- 
power at 2,000 revolutions per minute, an increase of 33 
brake horse-power. To utilize this increase in horse- 
power, a matter of some fifteen pounds must be spent 
in gearing and another fifteen perhaps on larger valves, 
bearings, etc. Two per cent, may be assumed lost in 
the gears. In other words, the increase in horse-power 
due to increasing the speed has been attained at the 
expense of about one pound per brake horse-power. 

The advantages of the eight-cylinder engine over the 
six and twelve, briefly stated, are : lower weight per horse- 
power, shorter length, simpler and stiffer crank-shaft, 
cam-shaft and crank-case, and simpler and more direct 
manifold arrangement. As to torque, the eight is supe- 
rior to the six, and yet in practice not enough inferior 
to the twelve to warrant the addition of four more 
cylinders. It must, however, be recognized that the 
eight is subject to the action of inherent unbalanced 
inertia couples, which set up horizontal vibrations, im- 
possible of total elimination. These vibrations are func- 
tions of the reciprocating weights, which, as already 
mentioned, are cut down to the minimum. Vibrations 
due to the elasticity of crank-case, crank-shaft, etc., can 
be and are reduced in the Thomas engine to minor 
quantities by ample webbing of the crank-case and judi- 



Thomas-Morse Engine 523 

cious use of metal elsewhere. All things considered, 
there is actually so little difference to be discerned be- 
tween the balance of a properly designed eight-cylinder 
engine and that of a six or twelve as to make a dis- 
cussion of the pros and cons more one of theory than 
of practice. 

The main criticisms of the L head cylinder engine are 
that it is less efficient and heavier. This is granted, as it 
relates to cylinders alone. More thorough investigation, 
however, based on the main desideratum, weight-power 
ratio, leads us to other conclusions, particularly with 
reference to high speed engines. The valve gear must 
not be forgotten. A cylinder cannot be taken completely 
away from its component parts and judged, as to its 
weight value, by itself alone. A part away from the whole 
becomes an item unimportant in comparison with the 
whole. The valve gear of a high speed engine is a too 
often overlooked feature. The stamp of approval has 
been made by high speed automobile practice upon the 
overhead cam-shaft drive, with valves in the cylinder 
head operated direct from the cam-shaft or by means of 
valve lifters or short rockers. 

The overhead cam-shaft mechanism applied to an 
eight-cylinder engine calls for two separate cam-shafts 
carried above and supported by the cylinders in an oil- 
tight housing, and driven by a series of spur gears or 
bevels from the crank-shaft. It is patent that this valve 
gearing is heavy and complicated in comparison with 
the simple moving valve units of the L head engine, 
which are operated from one single cam-shaft, housed 
rigidly in the crank-case. The inherently lower volu- 
metric efficiency of the L head engine is largely overcome 
by the use of a properly designed head, large valves and 
ample gas passages. Again, the customary use of a dual 
ignition system gives to the L head a relatively better 
opportunity for the advantageous placing of spark-plugs, 
in order that better flame propagation and complete 
combustion may be secured. 



524 



Aviation Engines 



The Thomas Model 88 engine is 4%-inch bore and 
5%-inch stroke. The cylinders and cylinder heads are 
of aluminum, and as steel liners are used in the cylinders 







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Fig. 233. — End View of Thomas-Morse 150 Horse-Power Aluminum Cylinder 
Aviation Motor Having Detachable Cylinder Heads. 



the pistons are also made of aluminum. This engine is 
actually lighter than the earlier model of less power. 
It weighs but 525 pounds, with self-starter. The general 



Siocte en-Valve Dues enb erg Engine 



525 



features of design can be readily ascertained by study 
of the illustrations: Fig. 233, which shows an end view; 
Fig. 234, which is a side view, and Fig. 235, which out- 




Fig. 234. — Side View of Thomas-Morse High Speed 150 Horse-Power 
Aviation Motor with Geared Down Propeller Drive. 

lines the reduction gear-case and the propeller shaft 
supporting bearings. 



SIXTEEN-VALVE DUESENBERG ENGINE 

This engine is a four-cylinder, 4%"x7", 125 horse- 
power at 2,100 K. P. M. of the crank-shaft and 1,210 
E. P. M. of the propeller. Motors are sold on above 
rating; actual power tests prove this motor capable of 
developing 140 horse-power at 2,100 E. P. M. of the 
motor. The exact weight with magneto, carburetor, gear 
reduction and propeller hub, as illustrated, 509 pounds; 
without gear reduction, 436 pounds. This motor has 
been produced as a power plant weighing 3.5 pounds per 
horse-power, yet nothing has been sacrificed in rigidity 
and strength. At its normal speed it develops 1 horse- 



526 



Aviation Engines 



power for every 3.5 cubic inches piston displacement. 
Cylinders are semi-steel, with aluminum plates enclosing 
water jackets. Pistons specially ribbed and made of 
Magnalite aluminum compound. Piston rings are special 
Duesenberg design, being three-piece rings. Valves are 




Fig. 235. — The Reduction Gear-Case of Thomas-Morse 150 Horse-Power 
Aviation Motor, Showing Ball Bearing and Propeller Drive Shaft Gear. 

tungsten steel, l 1 %e // inlets and 2" exhausts, two of each 
to each cylinder. Arranged horizontally in the head, 
allowing very thorough water- jacketing. Inlet valves in 
cages. Exhaust valves, seating directly in the cylinder 
head, are removable through the inlet valve holes. Valve 
stems lubricated by splash in the valve action covers. 
Valve rocker arms forged with cap screw and nut at 



Siocte en-Valve JDuesenberg Engine 527 

upper end to adjust clearance. Entirely enclosed by 
aluminum housing, as is entire valve mechanism. Con- 
necting rods are tubular, chrome nickel steel, light and 
strong. Crank-shaft is one-piece forging, hollow bored, 
2 1 /£-inch diameter at main bearings. Connecting rod 
bearings, 214-inch diameter, 3 inches long. Front main 
bearing, 3% inches long; intermediate main bearing, 
3y 2 inches long ; rear main bearing, 4 inches long. Crank- 
case of aluminum, barrel type, oil pan on bottom remov- 
able. Hand hole plates on both sides. Strongly webbed. 
The oiling system of this sixteen-valve Duesenberg 
motor is one of its vital features. An oil pump located 
in the base and submerged in oil forces oil through cored 
passages to the three main bearings, then through tubes 
under each connecting rod into which the rod dips. The 
oil is thrown off from these and lubricates every part of 
the motor. This constitutes the main oiling system; it is 
supplemented by a splash system, there being a trough 
under each connecting rod into which the rod slips. The 
oil is returned to the main supply sump by gravity, 
where it is strained and re-used. Either system is in 
itself sufficient to operate the motor. A pressure gauge 
is mounted for observation on a convenient part of the 
system. A pressure of approximately 25 pounds is 
maintained by the pressure system, which insures effi- 
cient lubrication at all speeds of the motor. The troughs 
under the connecting rods are so constructed that no 
matter what the angle of flight may be, oil is retained 
in each individual trough so that each connecting rod 
can dip up its supply of oil at each revolution. 

AEROMARINE SIX-CYLINDER VERTICAL MOTOR 

These motors are four-stroke cycle, six-cylinder ver- 
tical type, with cylinder 4 , >i/ / bore by 5%" stroke. The 
general appearance of this motor is shown in illustra- 
tion at Fig. 236. This engine is rated at 85-90 horse- 
power. All reciprocating and revolving parts of this 



528 



Aviation Engines 






motor are made of the highest grades of steel obtainable 
as are the studs, mits and bolts. The upper and lower 
parts of crank-case are made of composition aluminum 
casting. Lower crank-case is made of high grade alu- 
minum composition casting and is bolted directly to the 
upper half. The oil reservoir in this lower half casting 
provides sufficient oil capacity for five hours' continuous 
running at full power. Increased capacity can be pro- 



Motgnetc 



Water Pipe 



Individual 
Cylinders 




Water / 
Pump 



Oil Pump. 



Fig. 236. — The Six-Cylinder Aeromarine Engine. 



vided if needed to meet greater endurance requirements. 
Oil is forced under pressure to all bearings by means of 
high-pressured duplex-geared pumps. One side of this 
pump delivers oil under pressure to all the bearings, 
while the other side draws the oil from the splash case 
and delivers it to the main sump. The oil reservoir is 
entirely separate from the crank-case chamber. Under 
no circumstances will oil flood the cylinder, and the oiling 
system is not affected in any way by any angle of flight 
or position of motor. An oil pressure gauge is placed 
on instrument board of machine, which gives at all times 



Aeromarine Aviation Engine 529 

the pressure in oil system, and a sight glass at lower 
half of case indicates the amonnt of oil contained. The 
oil pump is external on magneto end of motor, and is 
very accessible. An external oil strainer is provided, 
which is removable in a few minutes ' time without the 
loss of any oil. All oil from reservoir to the motor passes 
through this strainer. Pressure gauge feed is also at- 
tached and can be piped to any part of machine desired. 

The cylinders are made of high-grade castings and 
are machined and ground accurately to size. Cylinders 
are bolted to crank-case with chrome nickel steel studs 
and nuts which securely lock cylinder to upper half of 
crank-case. The main retaining cylinder studs go 
through crank-case and support crank-shaft bearings so 
that crank-shaft and cylinders are tied together as one 
unit. Water jackets are of copper, % 6 " thick, electrically 
deposited. This makes a non-corrosive metal. Cooling 
is furnished by a centrifugal pump, which delivers 25 
gallons per minute 1,400 R. P. M. Pistons are made 
cast iron, accurately machined and ground to exact di- 
mensions, which are carefully balanced. Piston rings are 
semi-steel rings of Aeromarine special design. 

Connecting rods are of chrome nickel steel, H-section. 
Crank-shaft is made of chrome nickel steel, machined all 
over, and cut from solid billet, and is accurately bal- 
anced through the medium of balance weights being 
forged integral with crank. It is drilled for lightness and 
plugged for force feed lubrication. There are seven 
main bearings to crank-shaft. All bearings are of high- 
grade babbitt, die cast, and are interchangeable and easily 
replaced. The main bearings of the crank-shaft are 
provided with a single groove to take oil under pressure 
from pressure tube which is cast integral with case. 
Connecting rod bearings are of the same type. The 
gudgeon pin is hardened, ground and secured in con- 
necting rod, and is allowed to work in piston. Cam-shaft 
is of steel, with cams forged integral, drilled for light- 
ness and forced-feed lubrication, and is case-hardened. 



530 



Aviation Engines 




Fig. 237. — Tlie Wisconsin Aviation Engine, at Top, as Viewed from 
Carburetor Side. Below, the Exhaust Side. 



Wisconsin Aviation Engine 



531 



The bearings of cam-shaft are of bronze. Magneto, two 
high-tension Bosch D. U. 6. The intake manifold for 
carburetors are alnminnm castings and are so designed 
that each carburetor feeds three cylinders, thereby insur- 
ing easy flow of vapor at all speeds. Weight, 420 pounds. 

WISCONSIN" AVIATION ENGINES 

The new six-cylinder Wisconsin aviation engines, one 
of which is shown at Fig. 237, are of the vertical type, 




Fig. 238. — Dimensioned End Elevation of Wisconsin Six Motor. 

with cylinders in pairs and valves in the head. Dimen- 
sioned drawings of the six-cylinder vertical type are 
given at Figs. 238 and 239. The cylinders are made of 
aluminum alloy castings, are bored and machined and 
then fitted with hardened steel sleeves about Viq inch in 
thickness. After these sleeves have been shrunk into 
the cylinders, they are finished by grinding in place. 
Gray iron valve seats are cast into the cylinders. The 
valve seats and cylinders, as well as the valve ports, are 



532 



Aviation Engines 



entirely surrounded by water jackets. The valves set 
in the heads at an angle of 25° from the vertical, are 
made of tungsten steel and are provided with double 
springs, the outer or main spring and the inner or aux- 
iliary spring, which is used as a precautionary measure 
to prevent a valve falling into the cylinder in remote 
case of a main spring breaking. The cam-shaft is made 
of one solid forging, case-hardened. It is carried in an 




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BW 



into 
LD 
ru 




Mfr«— 5« 



Fig. 239. — Dimensioned Side Elevation of Wisconsin Six Motor. 



aluminum housing bolted to the top of the cylinders. 
This housing is split horizontally, the upper half carrying 
the chrome vanadium steel rocker levers. The lower half 
has an oil return trough cast integral, into which the 
excess oil overflows and then drains back to the crank- 
case. Small inspection plates are fitted over the cams 
and inner ends of the cam rocker levers. The cam-shaft 
runs in bronze bearings and the drive is through ver- 
tical shaft and bevel gears. 

The crank-case is made of aluminum, the upper half 



Wisconsin Aviation Engine 533 

carrying the bearings for the crank-shaft. The lower 
half carries the oil sump in which all of the oil except 
that circulating through the system at the time is carried. 
The crank- shaft is made of chrome vanadium steel of 
an elastic limit of 115,000 pounds. The crank-pins and 
ends of the shaft are drilled for lightness and the cheeks 
are also drilled for oil circulation. The crank-shaft runs 
in bronze-backed, Fahrig metal-lined bearings, four in 
number. A ' double thrust bearing is also provided, so 
that the motor may be used either in a tractor or pusher 
type of machine. Outside of the thrust bearing an annu- 
lar ball bearing is used to take the radial load of the 
propeller. The propeller is mounted on a taper. At the 
opposite end of the shaft a bevel gear is fitted which 
drives the cam-shaft, through a vertical shaft, and also 
drives the water and oil pumps and magnetos. All gears 
are made of chrome vanadium steel, heat-treated. 

The connecting rods are tubular and machined from 
chrome vanadium steel forgings. Oil tubes are fitted to 
the rods which carry the oil up to the wrist-pins and 
pistons. The rods complete with bushings weigh 5y 2 
pounds each. The pistons are made of aluminum alloy 
and are very light and strong, weighing only 2 pounds 
2 ounces each. Two leak-proof rings are fitted to each 
piston. The wrist-pins are hollow, of hardened steel, 
and are free to turn either in the piston or the rod. A 
bronze bushing is fitted in the upper end of the rod, but 
no bushing is fitted in the pistons, the hardened steel 
wrist-pins making an excellent bearing in the aluminum 
alloy. 

The water circulation is by centrifugal pump, which 
is mounted at the lower end of the vertical shaft. The 
water is pumped through brass pipes to the lower end 
of the cylinder water jackets and leaves the upper end 
of the jackets just above the exhaust valves. The lubri- 
cating system is one of the main features of the engines, 
being designed to work with the motor at any angle. 
The oil is carried in the sump, from where it is taken 



534 



Aviation Engines 



by the oil circulating pump through a strainer and forced 
through a header, extending the full length of the crank- 
case, and distributed to the main bearings. From the 
main bearings it is forced through the hollow crank- 
shaft to the connecting rod big ends and then through 



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100 

90 
80 

70 

ZOO 400 600 800 1000 IZOO 1400 1600 J8CJ0 2000 2200 Z400 
Revolutions per Minute 



800 

750 

700 

650 

600 

550 

500 1 

450: 

400 

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Fig. 240. — Power, Torque and Efficiency Curves of Wisconsin Aviation 

Motor. 



Wisconsin Aviation Engine 



535 



tubes on the rods to wrist-pins and pistons. Another 
lead takes oil from the main header to the cam-shaft 
bearings. The oil forced ont of the ends of the cam- 
shaft bearings fills pockets under the cams and in the 
cam rocker levers. The excess flows back through pipes 
and through the train of gears to the crank-case. A 
strainer is fitted at each end of the crank-case, through 
which the oil is drawn by separate pumps and returned 
to the sump. Either one of these pumps is large enough 





-> 


k— - Exhaust Closes 
IO°U- Inlet Opens 




~~ — > 

Firing Order 


I-4-2-6-3S 



Fig. 241. — Timing Diagram, Wisconsin Aviation Engine. 



to take care of all of the return oil, so that the operation 
is perfect whether the motor is inclined up or down. No 
splash is used in the crank-case, the system being a 
full force feed. An oil level indicator is provided, show- 
ing the amount of oil in the sump at all times. The oil 
pressure in these motors is carried at ten pounds, a 
relief valve being fitted to hold the pressure constant. 

Ignition is by two Bosch magnetos, each on a separate 
set of plugs fired simultaneously on opposite sides of the 
cylinders. Should one magneto fail, the other would still 
run the engine at only a slight loss in power. The Zenith 
double carburetor is used, three cylinders being supplied 
by each carburetor. This insures a higher volumetric 
efficiency, which means more power, as there is no over- 



536 Aviation Engines 

lapping of inlet valves whatever by this arrangement. 
All parts of these motors are very accessible. The water 
and oil pumps, carburetors, magnetos, oil strainer or 
other parts can be removed without disturbing other 
parts. The lower crank-case can be removed for in- 
spection or adjustment of bearings, as the crank-shaft and 
bearing caps are carried by the upper half. The motor 
supporting lugs are also part of the upper crank-case. 

The six-cylinder motor, without carburetors or mag- 
netos, weighs 547 pounds. With carburetor and mag- 
netos, the weight is 600 pounds. The weight of cooling 
water in the motor is 38 pounds. The sump will carry 
4 gallons of oil, or about 28 pounds. A radiator can be 
furnished suitable for the motor, weighing 50 pounds. 
This radiator will hold 3 gallons of water or about 25 
pounds. The motor will drive a two-blade, 8 feet diame- 
ter by 6.25 feet pitch Paragon propeller 1400 revolutions 
per minute, developing 148 horse-power. The weight of 
this propeller is 42 pounds. This makes a total weight 
of motor, complete with propeller, radiator filled with 
water, but without lubricating oil, 755 pounds, or about 
5.1 pounds per horse-power for complete power plant. 
The fuel consumption is .5 pound per horse-power per 
hour. The lubricating oil consumption is .0175 pound 
per horse-power per hour, or a total of 2.6 pounds per 
hour at 1400 revolutions per minute. This would make 
the weight of fuel and oil, per hour's run at full power 
at 1400 revolutions per minute, 76.6 pounds. 

PRINCIPAL DIMENSIONS 

Following are the principal dimensions of the six- 
cylinder motor: 

Bore 5 inches. 

Stroke 6y 2 inches. 

Crank-shaft diameter throughout 2 inches. 

Length of crank-pin and main bearings 3y 2 inches. 

Diameter of valves 3 inches (2% inches clear). 



Wisconsin Aviation Engine 537 

Lift of valves y 2 inch. 

Volume of compression space 22 per cent, of total. 

Diameter of wrist-pins 1%6 inches. 

Firing order 1-4-2-6-3-5. 

The horse-power developed at 1200 revolutions per 
minute is 130, at 1300 revolutions per minute 140, at 
1400 revolutions per minute 148. 1400 is the maximum 
speed at which it is recommended to run these motors. 

TWELVE-CYLINDER ENGINE 

A twelve -cylinder V-type engine illustrated, is also 
being built by this company, similar in dimensions of 
cylinders to the six. The principal differences being in 
the drive to cam-shaft, which is through spur gears in- 
stead of bevel. A hinged type of connecting rod is used 
which does not increase the length of the motor and, at 
the same time, this construction provides for ample bear- 
ings. A double centrifugal water pump is provided for 
this motor, so as to distribute the water uniformly to 
both sets of cylinders. Four magnetos are used, two for 
each set of six cylinders. The magnetos are very acces- 
sibly located on a bracket on the spur gear cover. The 
carburetors are located on the outside of the motors, 
where they are very accessible, while the exhaust is in the 
center of the valley. The crank-shaft on the twelve is 
2y 2 inches in diameter and the shaft is bored to reduce 
weight. Dimensioned drawings of the twelve-cylinder 
engine are given at Figs. 242 and 243 and should prove 
useful for purposes of comparison with other motors. 

HALL-SCOTT AVIATION ENGINES 

The following specifications of the Hall-Scott "Big 
Four" engines apply just as well to the six-cylinder 
vertical types which are practically the same in construc- 
tion except for the structural changes necessary to ac- 
commodate the two extra cylinders. Cylinders are cast 



538 



Aviation Engines 



separately from a special mixture of semi-steel, having 
cylinder head with valve seats integral. Special attention 
has been given to the design of the water jacket around 
the valves and head, there being two inches of water 




Fig. 242. — Dimensioned End View of Wisconsin Twelve-Cylinder Airplane 

Motor. 



space above same. The cylinder is annealed, rough ' 
machined, then the inner cylinder wall and valve seats 
ground to mirror finish. This adds to the durability of 
the cylinder, and diminishes a great deal of the excess 
friction. 



Hall-Scott Engines 



539 



Great care is taken in the casting and machining of 
these cylinders, to have the bore and walls concentric 
with each other. Small ribs are cast between outer and 
inner walls to assist cooling as well as to transfer stresses 
direct from the explosion to hold-down bolts which run 
from steel main bearing caps to top of cylinders. The 
cylinders are machined upon the sides so that when 
assembled on the crank-case with grooved hold-down 




Fig. 243. — Dimensioned Side Elevation of Wisconsin Twelve-Cylinder Air- 
plane Motor. 

washers tightened, they form a solid block, greatly assist- 
ing the rigidity of crank-case. 

The connecting rods are very light, being of the I 
beam type, milled from a solid Chrome nickel die forging. 
The caps are held on by two %"-20 thread Chrome nickel 
through bolts. The rods are first roughed out, then an- 
nealed. Holes are drilled, after which the rods are hard- 
ened and holes ground parallel with each other. The 
piston end is fitted with a gun metal bushing, while the 
crank-pin end carries two bronze serrated shells, which 
are tinned and babbitted hot, being broached to harden 
the babbitt. Between the cap and rod proper are placed 



54<0 Aviation Engines 

laminated shims for adjustment. Crank-cases are cast of 
the best aluminum alloy, hand scraped and sand blasted 
inside and out. The lower oil case can be removed with- 
out breaking any connections, so that the connecting rods 
and other working parts can readily be inspected. An 
extremely large strainer and dirt trap is located in the 
center and lowest point of the case, which is easily re- 
moved from the outside without disturbing the oil pump 
or any working parts. A Zenith carburetor is provided. 
Automatic valves and springs are absent, making the 
adjustment simple and efficient. This carburetor is not 
affected by altitude to any appreciable extent. A Hall- 
Scott device, covered by U. S. Patent No. 1,078,919, allows 
the oil to be taken direct from the crank-case and run 
around the carburetor manifold, which assists carburetion 
as well as reduces crank-case heat. Two waterproof four- 
cylinder Splitdorf " Dixie' ' magnetos are provided. Both 
magneto interruptors are connected to a rock shaft in- 
tegral with the motor, making outside connections unneces- 
sary. It is worthy of note that with this independent 
double magneto system, one complete magneto can become 
inoperative, and still the motor will run and continue to 
give good power. 

The pistons as provided in the A-7 engines are cast 
from a mixture of steel and gray iron. These are ex- 
tremely light, yet provided with six deep ribs under the 
arch head, greatly aiding the cooling of the piston as well 
as strengthening it. The piston pin bosses are located 
very low in order to keep the heat from the piston head 
away from the upper end of the connecting rod, as well 
as to arrange them at the point where the piston fits the 
cylinder best. Three 14" rings are carried. The pistons 
as provided in the A-7a engines are cast from aluminum 
alloy. Four *4" rings are carried. In both piston types 
a large diameter, heat treated, Chrome nickel steel wrist- 
pin is provided, assembled in such a way as to assist the 
circular rib between the wrist-pin bosses to keep the 
piston from being distorted from the explosions. 



Hall-Scott Engines 541 

The oiling system is known as the high pressure type, 
oil being forced to the nnder side of the main bearings 
with from 5 to 30 points pressure. This system is not 
affected by extreme angles obtained in flying, or whether 
the motor is used for push or pull machines. A large 
gear pump is located in the lowest point of the oil sump, 
and being submerged at all times with oil, does away 
with troublesome stuffing boxes and check valves. The 
oil is first drawn from the strainer in oil sump to the long 
jacket around the intake manifold, then forced to the 
main distributor pipe in crank-case, which leads to all 
main bearings. A bi-pass, located at one end of the 
distributor pipe, can be regulated to provide any pres- 
sure required, the surplus oil being returned to the case. 
A special feature of this system is the dirt, water and 
sediment trap, located at the bottom of the oil sump. 
This can be removed without disturbing or dismantling 
the oil pump or any oil pipes. A small oil pressure gauge 
is provided, which can be run to the aviator's instrument 
board. This registers the oil pressure, and also deter- 
mines its circulation. 

The cooling of this motor is accomplished by the oil 
as well as the water, this being covered by patent No. 
1,078,919. This is accomplished by circulating the oil 
around a long intake manifold jacket; the carburetion 
of gasoline cools this regardless of weather conditions. 
Crank-case heat is therefore kept at a minimum. The 
uniform temperature of the cylinders is maintained by 
the use of ingenious internal outlet pipes, running through 
the head of each of the six-cylinders, rubber hose con- 
nections being used so that any one of the cylinders may 
be removed without disturbing the others. Slots are cut 
in these pipes so that cooler water is drawn directly 
around the exhaust valves. Extra large water jackets 
are provided upon the cylinders, two inches of water 
space is left above the valves and cylinder head. The 
water is circulated by a large centrifugal pump insuring 
ample circulation at all speeds. 



542 Aviation Engines 

The crank-shaft is of the five bearing type, being 
machined from a special heat treated drop forging of the 
highest grade nickel steel. The forging is first drilled, 
then roughed ont. After this the shaft is straightened, 
turned down to a grinding size, then ground accurately 
to size. The bearing surfaces are of extremely large 
size, over-size, considering general practice in the build- 
ing of high speed engines of similar bore and stroke. 
The crank-shaft bearings are 2" in diameter by 1 15 /iq" 
long, excepting the rear main bearing, which is 4%" 
long, and front main bearing, which is 2% 6 " long. Steel 
oil scuppers are pinned and sweated onto the webs of 
the shaft, which allows of properly oiling the connecting 
rod bearings. Two thrust bearings are installed on the 
propeller end of the shaft, one for pull and the other for 
push. The propeller is driven by the crank- shaft flange, 
which is securely held in place upon the shaft by six 
keys. These drive an outside propeller flange, the pro- 
peller being clamped between them by six through bolts. 
The flange is fitted to a long taper on crank-shaft. This 
enables the propeller to be removed without disturbing 
the bolts. Timing gears and starting ratchets are bolted 
to a flange turned integral with shaft. 

The cam-shaft is of the one piece type, air pump 
eccentric, and gear flange being integral. It is made 
from a low carbon specially heat treated nickel forging, 
is first roughed out and drilled entire length; the cams 
are then formed, after which it is case hardened and 
ground to size. The cam-shaft bearings are extra long, 
made from Parson's White Brass. A small clutch is 
milled in gear end of shaft to drive revolution indicator. 
The cam-shaft is enclosed in an aluminum housing bolted 
directly on top of all six cylinders, being driven by a 
vertical shaft in connection with bevel gears. This shaft, 
in conjunction with rocker arms, rollers and other work- 
ing parts, are oiled by forcing the oil into end of shaft, 
using same as a distributor, allowing the surplus supply 
to flow back into the crank-case through hollow vertical 



Hall- Scott Engine Details 543 

tube. This supply oils the magneto and pump gears. 
Extremely large Tungsten valves, being one-half the cylin- 
der diameter, are seated in the cylinder heads. Large 
diameter oil tempered springs held in tool steel cups, 
locked with a key, are provided. The ports are very 
large and short, being designed to allow the gases to en- 
ter and exhaust with the least possible resistance. These 
valves are operated by overhead one piece cam-shaft in 
connection with short Chrome nickel rocker arms. These 
arms have hardened tool steel rollers on cam end with 
hardened tool steel adjusting screws opposite. This con- 
struction allows accurate valve timing at all speeds with 
least possible weight. 



CENSORED 



GEBMA2* AIRPLAXE MOTORS 

In a paper on "Aviation Motors," presented by E. H. 
Sherbondy before the Cleveland section of the S. A. E. 
in June, 1917, the Mercedes and Benz airplane motor is 
discussed in some detail and portions of the description 
follow. 

MERCEDES MOTOR 

The 150 horse-power six-cylinder Mercedes motor is 
140 millimeters bore and 160 millimeters stroke. The 
Mercedes company started with smaller-sized cylinders, 
namely 100 millimeters bore and 140 millimeters stroke, 
six-cylinders. The principal features of the design are 
forged steel cylinders with forged steel elbows for gas 
passages, pressed steel water jackets, which when welded 



544 Aviation Engines 






CENSORED 






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Aviation Engines 



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548 Aviation Engines 

together forms the cylinder assembly, the use of inclined 
overhead valves operated by means of an overhead cam- 
shaft through rocker arms which multiply with the mo- 
tion of the cam. By the use of steel cylinders, not only 
is the weight greatly reduced, but certain freedom from 
distortion through unequal sections, leaks and cracks are 
entirely avoided. The construction is necessarily very 
expensive. It is certainly a sound job. In the details 
of this construction there are a number of important 
things, such as finished gas passages, water-cooled valve 
guides and a very small mass of metal, which is water- 
cooled, surrounding the spark-plug. Of course, it is nec- 
essary to use very high compression in aviation motors 
in order to secure high power and economy and owing to 
the fact that aviation motors are worked at nearly their 
maximum, the heat flow through the cylinder, piston, and 
valves is many times higher than that encountered in 
automobile motors. It has been found necessary to de- 
velop special types of pistons to carry the heat from the 
center of the head in order to prevent pre-ignition. In 
the Mercedes motor the pistons have a drop forged steel 
head which includes the piston boss and this head is 
screwed into a cast iron skirt which has been machined 
inside to secure uniform wall thickness. 

The carburetor used on this 150 horse-power Mer- 
cedes motor is precisely of the same type used on the 
Twin Six motor. It has two venturi throats, in the center 
of which is placed the gasoline spray nozzle of conven- 
tional type, fixed size orifices, immediately above which 
are placed two panel type throttles with side outlets. 
An idling or primary nozzle is arranged to discharge 
above the top of the venturi throat. -The carburetor 
body is of cast aluminum and is water jacketed. It is 
bolted directly to air passage passing through the top 
and bottom half of the crank-case which passes down 
through the oil reservoir. The air before reaching the 
carburetor proper to some extent has cooled the oil in 
the crank chamber and has itself been heated to assist 



Mercedes Engine Details 



549 



in the vaporization. The inlet pipes themselves are cop- 
per. All the passages between the ventnri throat and 
the inlet valve have been carefully finished and polished. 
The only abnormal thing in the design of this motor is 
the short connecting rod which is considerably less than 
twice the stroke and would be considered very bad practice' 
in motor car engines. A short connecting rod, however, 




Fig. 245. — Part Sectional View of 90 Horse-Power Mercedes Engine, 
Which is Typical of the Design of Larger Sizes. 



possesses two very real virtues in that it cuts down height 
of the motor and the piston passes over the bottom dead 
center much more slowly than with a long rod. 

Other features of the design are a very stiff crank- 
case, both halves of which are bolted together by means 
of long through bolts, the crank-shaft main bearings are 
seated in the lower half of the case instead of in the 
usual caps and no provision is made for taking up the 
main bearings. The Mercedes company uses a plunger 



550 Aviation Engines 

type of pump having mechanically operated piston valves 
and it is driven by means of worm gearing. 

The overhead cam-shaft construction is extremely 
light. The cam-shaft is mounted in a nearly cylindrical 
cast bronze case and is driven by means of bevel gears 
from the crank-shaft. The vertical bevel gear shaft 
through which the drive is taken from the crank-shaft to 
the cam-shaft operates at one and one-half times the 
crank- shaft speeds and the reduction to the half-time 
cam-shaft is secured through a pair of bevels. On this 
vertical shaft there is mounted the water pump and a 
bevel gear for driving two magnetos. The water pump 
mounted on this shaft tends to steady the drive and avoid 
vibration in the gearing. 

The cylinder sizes of six-cylinder aviation motors 
which have been built by Mercedes are 

Bore Stroke Horse-power 

105 mm. 140 mm. 100 

120 mm. 140 mm. 135 

140 mm. 150 mm. 150 

140 mm. 160 mm. 160 

The largest of these motors has recently had its horse- 
power increased to 176 at 1450 R. P. M. This general 
design of motor has been the foundation for a great many 
other aviation motor designs, some of which have proved 
very successful but none of which is equal to the origi- 
nal. Among the motors which follow more or less closely 
the scheme of design and arrangement are the Hall-Scott, 
the Wisconsin motor, the Renault water-cooled, the Pack- 
ard, the ChristofTerson and the Rolls-Royce. Each of 
these motors show considerable variation in detail. The 
Rolls-Royce and Renault are the only ones who have used 
the steel cylinder with the steel jacket. The "Wisconsin 
motor uses an aluminum cylinder Avith a hardened steel 
liner and cast-iron valve seats. The ChristofTerson has 
somewhat similar design to the Wisconsin with the ex- 
ception that the valve seats are threaded into the alumi- 



The Benz Motor 551 

num jacket and the cylinder head has a blank end which 
is secured to the aluminum casting by means of the valve 
seat pieces. The Eolls-Eoyce motors show small differ- 
ences in details of design in cylinder head and cam-shaft 
housing from the Mercedes on which it has taken out 
patents, not only abroad but in this country. 

THE BENZ MOTOR 

In the Kaiser prize contest for aviation motors a four- 
cylinder Benz motor of 130 by 180 mm. won first prize, 
developing 103 B. H. P. at 1290 K. P. M. The fuel con- 
sumption was 210 grams per horse-power hour. Total 
weight of the motor was 153 kilograms. The oil con- 
sumption was .02 of a kilogram per horse-power hour. 
This motor was afterward expanded into a six-cylinder 
design and three different sizes were built. 

The accompanying table gives some of the details of 
weight, horse-power, etc. 

Motor type B FD FF 

Rated horse-power 85 100 150 

Horse-power at 1250 r.p.m 88 108 150 

Horse-power at 1350 r.p.m 95 115 160 

Bore in millimeters 106 116 130 

Stroke in millimeters 150 160 180 

Offset of the cylinders in millimeters 18 20 20 

Rate of gasoline consumption in grams 240 230 225 

Oil consumption in grams per b.h.p. hour. ... 10 10 10 

Oil capacity in kilograms 36 4 4% 

Water capacity in litres 5V 2 iy 2 9 *£ 

The weight with water and oil but with two 

magnetos, fuel feeder and air pump in 

kilograms 170 200 245 

The weight of motors, including the water 

pump, two magnetos, double ignition, etc.. 160 190 230 
The weight of the exhaust pipe, complete in 

kilograms 4 4.8 5 % 

The weight of the propeller hub in kilograms. Zy 2 4 4 

The Benz cylinder is a simple, straightforward design 
and a very reliable construction and not particularly diffi- 
cult to manufacture. The cylinder is cast of iron without 



552 Aviation Engines 

a water jacket but including 45 degrees angle elbows to 
the valve ports. The cylinders are machined wherever 
possible and at other points have been hand filed and 
scraped, after which a jacket, which is pressed in two 
halves, is gas welded by means of short pipes welded on 
to the jacket. The bottom and the top of the cylinders 
become water galleries, and by this means separate water 
pipes with their attendant weight and complication are 
eliminated. Eubber rings held in aluminum clamps serve 
to connect the cylinders together. The whole construc- 
tion turns out very neat and light. The cylinder walls 
are 4 mm. or % 6 " thick and the combustion chamber is of 
cylindrical pancake form and is 140 mm. or 5.60 inch in 
diameter. The valve seats are 68 mm. in diameter and 
the valve port is 62 mm. in diameter. 

The passage joining the port is 57 mm. in diameter. 
In order to insert the valves into the cylinder the valve 
stem is made with two diameters and the valve has to 
be cocked to insert it in the guide, which has a bronze 
bushing at its upper end to compensate for the smaller 
valve stem diameter. The valve stem is 14 mm. or %6" 
in diameter and is reduced at its upper portion to 9% nim. 
The valves are operated through a push rod and rocker 
arm construction, which is Viq' and exceedingly light. 
Eocker arm supports are steel studs with enlarged heads 
to take a double row ball bearing. A roller is mounted 
at one end of the rocker arm to impinge on the end of 
the valve stem, and the rocker arm has an adjustable 
globe stud at the other end. The push rods are light steel 
tubes with a wall thickness of 0.75 mm. and have a hard- 
ened steel cup at their upper end to engage the rocker 
arm globe stud and a hardened steel globe at their lower 
end to socket in the roller plunger. 

The Benz cam-shaft has a diameter of 26 mm. and is 
bored straight through 18 mm. and there is a spiral gear 
made integrally with the shaft in about the center of its 
length for driving the oil pump gear. The cam faces are 
10 mm. wide. There is also, in addition to the intake 



The Benz Motor 553 

and exhaust cams, a set of half compression cams. The 
shaft is moved longitudinally in its bearings by means of 
an eccentric to put these cams into action. At the fore 
end of the shaft is a driving gear flange which is very 
small in diameter and very thin. The flange is 68 mm. 
in diameter and 4 mm. thick and is tapped to take 6 mm. 
bolts. The total length of cam-shaft is 1038 mm., and it 
becomes a regular gun boring job to drill a hole of this 
length. 

The cam-shaft gear is 140 mm. or 5% inches outside 
diameter. It has fifty-four teeth and the gear face is 15 
mm. or 1 %2". The flange and web have an average thick- 
ness of 4 mm. or %2 /f and the web is drilled full of holes 
interposed between the spur gear mounted on the cam- 
shaft and the cam-shaft gear. There is a gear which 
serves to drive the magnetos and tachometer, also the 
air pump. The shaft is made integrally with this gear 
and has an eccentric portion against which the air pump 
roll plunger impinges. 

The seven-bearing crank- shaft is finished all over in 
a beautiful manner, and the shaft out of the particular 
motor we have shows no signs of wear whatever. The 
crank-pins are 55 mm. in diameter and 69 mm. long. 
Through both the crank-pin and main bearings there is 
drilled a 28 mm. hole, and the crank cheeks are plugged 
with solder. The crank cheeks are also built to convey 
the lubricant to the crank-pins. At the fore end of the 
crank cheek there is pressed on a spur driving gear. 
There is screwed on to the front end of the shaft a piece 
which forms a bevel water pump driving gear and the 
starting dog. At the rear end of the shaft very close to 
the propeller hub mounting there is a double thrust bear- 
ing to take the propeller thrust. 

Long, shouldered studs are screwed into the top half 
of the crank-case portion of the case and pass clean 
through the bottom half of the case. The case is very 
stiff and well ribbed. The three center bearing dia- 
phragms have double walls. The center one serves as a 



554< Aviation Engines 

duct through which water pipe passes, and those on either 
side of the center form the carburetor intake air passages 
and are enlarged in section at one side to take the car- 
buretor barrel throttle. 

The pistons are of cast iron and carry three concentric 
rings 14 inch wide on their upper end, which are pinned 
at the joint. The top of the piston forms the frustum 
of the cone and the pistons are 110 mm. in length. The 
lower portion of the skirt is machined inside and has a 
wall thickness of 1 mm. Kiveted to the piston head is 
a conical diaphragm which contacts with the piston pin 
when in place and serves to carry the heat off the center 
of the piston. 

The oil pump assembly comprises a pair of plunger 
pumps which draw oil from a separate outside pump, and 
constructed integrally with it is a gear pump which de- 
livers the oil under about 60 pound pressure through a 
set of copper pipes in the base to the main bearings. The 
plunger oil pump shows great refinement of detail. A 
worm wheel and two eccentrics are machined up out of 
one piece and serve to operate the plungers. 

Some interesting details of the 160 horse-power Benz 
motor, which is shown at Fig. 246, are reproduced from 
the "Aerial Age "Weekly," and show how carefully the 
design has been considered. 

Maximum horse-power, 167.5 B. H. P. 

Speed at maximum horse-power, 1,500 E. P. M. 

Piston speed at maximum horse-power, 1,770 ft. per 
minute. 

Normal horse-power, 160 B. H. P. 

Speed at normal horse-power, 1,400 E. P. M. 

Piston speed at normal horse-power, 1,656 ft. per 
minute. 

Brake mean pressure at maximum horse-power, 101.2 
pound per square inch. 

Brake mean pressure at normal horse-power, 103.4 
pound per square inch. 



The Benz Motor 



555 




556 Aviation Engines 

Specific power cubic inch swept volume per B. H. P., 
5.46 cubic inch ; 160 B. H. P. 

Weight of piston, complete with gudgeon pin, rings, 
etc., 5.0 pound. 

Weight of connecting rod, complete with bearings, 
4.99 pound; 1.8 pound reciprocating. 

Weight of reciprocating parts per cylinder, 6.8 pound. 

Weight of reciprocating parts per square inch of 
piston area, 0.33 pound. 

Outside diameter of inlet valve, 68 mm. ; 2.68 inches. 

Diameter of inlet valve port (d), 61.5 mm.; 2.42 inches. 

Maximum lift of inlet valve (h), 11 mm., 0.443 inch. 

Area of inlet valve opening (tdk), 21.25 square cm.; 
3.29 square inches. 

Inlet valve opens, degrees on crank, top dead center. 

Inlet valve closes, degrees on crank, 60° late; 35 mm. 
late. 

Outside diameter of exhaust valve, 68 mm., 2.68 inches. 

Diameter of exhaust valve port (d), 61.5 mm.; 2!42 
inches. 

Maximum lift or exhaust valve (7i) 11 mm.; 0.433 
inch. 

Area of exhaust valve opening (^dh), 21.25 square 
cm.; 3.29 square inches. 

Exhaust valve opens, degrees on crank, 60° early; 
35 mm. early. 

Exhaust valve closes, degrees on crank, 16%° late; 
5 mm. late. 

Length of connecting rod between centers, 314 mm.; 
12.36 inches. 

Eatio connecting rod to crank throw, 3.49:1. 

Diameter of crank-shaft, 56 mm. outside, 2.165 inches; 
28 mm. inside, 1.102 inches. 

Diameter of crank-pin, 55 mm. outside, 2.165 inches; 
28 mm. inside, 1.102 inches. 

Diameter of gudgeon pin, 30 mm. outside, 1.181 inches ; 
19 mm. inside, 0.708 inch. 



Austro-Daimler Engine 557 

Diameter of cam-shaft, 26 mm. outside, 1.023 inches; 
18 mm. inside, 0.708 inch. 

Number of crank-shaft bearings, 7. 

Projected area of crank-pin bearings, 36.85 square 
cm. ; 5.72 square inches. 

Projected area of gudgeon pin bearings, 22.20 square 
cm.; 3.44 square inches. 

Firing sequence, 1, 5, 3, 6, 2, 4. 

Type of magnetos, ZH6 Bosch. 

Direction of rotation of magneto from driving end, 
one clock, one anti -clock. 

Magneto timing, full advance, 30° early (16 mm. 
early). 

Type of carburetors (2) Benz design. 

Fuel consumption per hour, normal horse-power, 0.57 
pint. 

Normal speed of propeller, engine speed, 1,400 E. P. M. 

AUSTRO-DAIMLER E^GI^E 

One of the first very successful European flying engines 
which was developed in Europe is the Austro-Daimler, 
which is shown in end section in a preceding chapter. The 
first of these motors had four-cylinders, 120 by 140 milli- 
meters, bore and stroke, with cast iron cylinders, over- 
head valves operated by means of a single rocker arm, 
controlled by two cams and the valves were closed by a 
single leaf spring which oscillates with the rocker arm. 
The cylinders are cast singly and have either copper or 
steel jackets applied to them. The four-cylinder design 
was afterwards expanded to the six-cylinder design and 
still later a six-cylinder motor of 130 by 175 millimeters 
was developed. This motor uses an offset crank-shaft, 
as does the Benz motor, and the effect of offset has been 
discussed earlier on in this treatise. The Benz motor also 
uses an offset cam-shaft which improves the valve opera- 
tion and changes the valve lift diagram. The lubrication 
also is different than any other aviation motor, since 



558 Aviation Engines 

individual high pressure metering pumps are used to 
deliver fresh oil only to the bearings and cylinders, as 
was the custom in automobile practice some ten years ago. 



SUNBEAM AVIATION ENGINES 

These very successful engines have been developed by 
Louis Coatalen. At the opening of the war the largest 
sized Coatalen motor was 225 horse-power and was of the 
L-head type having a single cam-shaft for operating 
valves and was an evolution from the twelve-cylinder 
racing car which the Sunbeam Company had previously 
built. Since 1914 the Sunbeam Company have produced 
engines of six-, eight-, twelve- and eighteen-cylinders from 
150 to 500 horse-power with both iron and aluminum 
cylinders. For the last two years all the motors have had 
overhead cam-shafts with a separate shaft for operating 
the intake and exhaust valves. Cam-shafts are connected 
through to the crank-shaft by means of a train of spur 
gears, all of which are mounted on two double row ball 
bearings. In the twin six, 350 horse-power engine, oper- 
ating at 2100 K. P. M., requires about 4 horse-power 
to operate the cam-shafts. This motor gives 362 horse- 
poAver at 2100 revolutions and has a fuel consumption of 
51 Aoo of a pint per brake horse-power hour. The cylinders 
are 110 by 160 millimeters. The same design has been 
expanded into an eighteen-cylinder which gives 525 horse- 
power at 2100 turns. There has also been developed a 
very successful eight-cylinder motor rated at 2220 horse- 
power which has a bore and stroke of 120 by 130 milli- 
meters, weight 450 pounds. This motor is an aluminum 
block construction with steel sleeves inserted. Three 
valves are operated, one for the inlet and two for the 
exhaust. One cam-shaft operates the three valves. 

The modern Sunbeam engines operate with a mean 
effective pressure of 135 pounds with a compression ratio 
of 6 to 1 sea level. The connecting rods are of the articu 
lated type as in the Eenault motor and are very short. 






Sunbeam Aviation Engines 



559 



The weight of these motors turns out at 2.6 pounds per 
brake horse-power, and they are able to go through a 
100 hour test without any trouble of any kind. The lubri- 
cating system comprises a dry base and oil pump for 




Fig. 247.— At Top, the Sunbeam Overhead Valve 170 Horse-Power Six- 
Cylinder Engine. Below, Side View of Sunbeam 350 Horse-Power 
Twelve-Cylinder Vee Engine. 

drawing the oil off from the base, whence it is delivered 
to the niter and cooling system. It then is pumped by a 
separate high pressure gear pump through the entire 
motor. In these larger European motors, castor-oil is 



560 



Aviation Engines 




Sunbeam Aviation Engines 



561 



used largely for lubrication. It is said that without the 
use of castor-oil it is impossible to hold full power for 
five hours. Coatalen favors aluminum cylinders rather 
than cast iron. The series of views in Figs. 247 to 250 
inclusive, illustrates the vertical, narrow type of engine ; 
the V-form; and the broad arrow type wherein three 




Fig. 249. — Sunbeam Eighteen-Cylinder Motor, Viewed from Pump and 

Magneto End. 

rows, each of six-cylinders, are set on a common crank- 
case. In this water-cooled series the gasoline and oil 
consumption are notably low, as is the weight per horse- 
power. 

In the eighteen-cylinder overhead valve Sunbeam- 
Coatalen aircraft engine of 475 brake horse-power, there 
are no fewer than half a dozen magnetos. Each magneto 
is inclosed. Two sparks are furnished to each cylinder 



562 



Aviation Engines 



from independent magnetos. On this engine there are 
also no fewer than six carburetors. Shortness of crank- 
shaft, and therefore of engine length, and absence of 
vibration are achieved by the linking of the connecting- 
rods. Those concerned with three-cylinders in the broad 
arrow formation work on one crank-pin, the outer rods 
being linked to the central master one. In consequence 




Fig. 250. — Propeller End of Sunbeam Eighteen-Cylinder 475 B.H.P. 
Aviation Engine. 



of this arrangement, the piston travel in the case of the 
central row of cylinders is 160 mm., while the stroke of 
the pistons of the cylinders set on either side is in each 
case 168 mm. Inasmuch as each set of six-cylinders is 
completely balanced in itself, this difference in stroke 
does not affect the balance of the engine as a whole. The 



Indicating Meters 563 

duplicate ignition scheme also applies to the twelve- 
cylinder 350 brake horse-power Sunbeam-Coatalen over- 
head valve aircraft engine type. It is distinguishable, 
incidentally, by the passage formed through the center of 
each induction pipe for the sparking plug in the center 
cylinder of each block of three. In this, as in the eighteen- 
cylinder and the six-cylinder types, there are two cam- 
shafts for each set of cylinders. These cam-shafts are 
lubricated by low pressure and are operated through a 
train of inclosed spur wheels at the magneto end of the 
machine. The six-cylinder, 170 brake horse-power vertical 
type employs the same general principles, including the 
detail that each carburetor serves gas to a group of three- 
cylinders only. It will be observed that this engine pre- 
sents notably little head resistance, being suitable for 
multi-engined aircraft. 



INDICATING METERS FOR AUXILIARY SYSTEMS 

The proper functioning of the power plant and the 
various groups comprising it may be readily ascertained 
at any time by the pilot because various indicating meters 
and pressure gauges are provided which are located on a 
dash or cowl board in front of the aviator, as shown at 
Fig. 251. The speed indicator corresponds to the speedom- 
eter of an automobile and gives an indication of the speed 
the airplane is making, which taken in conjunction with the 
clock will make it possible to determine the distance cov- 
ered at a flight. The altimeter, which is an aneroid 
barometer, outlines with fair accuracy the height above 
the ground at which a plane is flying. These instruments 
are furnished to enable the aviator to navigate the air- 
plane when in the air, and if the machine is to be used 
for cross-country flying, they may be supplemented by a 
compass and a drift set. It will be evident that these 
are purely navigating instruments and only indicate the 
motor condition in an indirect manner. The best way of 
keeping track of the motor action is to watch the tachom- 



564< 



Aviation Engines 







Compressed Air-Starting Systems 565 

eter or revolution counter which is driven from the 
engine by a flexible shaft. This indicates directly the 
number of revolutions the engine is making per minute 
and, of course, any slowing up of the engine in normal 
flights indicates that something is not functioning as it 
should. The tachometer operates on the same principle 
as the speed indicating device or speedometer used in 
automobiles except that the dial is calibrated to show 
revolutions per minute instead of miles per hour. At the 
extreme right of the dash at Fig. 251 the spark advance 
and throttle control levers are placed. These, of course, 
regulate the motor speed just as they do in an automobile. 
Xext to the engine speed regulating levers is placed a 
push button cut-out switch to cut out the ignition and 
stop the motor. Three pressure gauges are placed in a 
line. The one at the extreme right indicates the pressure 
of air on the fuel when a pressure feed system is used. 
The middle one shows oil pressure, while that nearest 
the center of the dash board is employed to show the air 
pressure available in the air starting system. It will be 
evident that the character of the indicating instruments 
will vary with the design of the airplane. If it was pro- 
vided with an electrical starter instead of an air system 
electrical indicating instruments would have to be pro- 
vided. 

COMPRESSED AIR- STARTING SYSTEMS 

Two forms of air-starting systems are in general use, 
one in which the crank-shaft is turned by means of an 
air motor, the other class where compressed air is ad- 
mitted to the cylinders proper and the motor turned over 
because of the air pressure acting on the engine pistons. 
A system known as the "Never-Miss" utilizes a small 
double-cylinder air pump is driven from the engine by 
means of suitable gearing and supplies air to a substan- 
tial container located at some convenient point in the 
fuselage. The air is piped from the container to a dash- 
control valve and from this member to a peculiar form 



566 Aviation Engines 

of air motor mounted near the crank-shaft. The air 
motor consists of a piston to which a rack is fastened 
which engages a gear mounted on the crank shaft pro- 
vided with some form of ratchet clutch to permit it to 
revolve only in one direction, and then only when the 
gear is turning faster than the engine crank-shaft. 

The method of operation is extremely simple, the 
dash-control valve admitting air from the supply tank 
to the top of the pump cylinder. When in the position 
shown in cut the air pressure will force the piston and 
rack down and set the engine in motion. A variety of 
air motors are used and in some the pump and motor may 
be the same device, means being provided to change the 
pump to an air motor when the engine is to be turned over. 

The "Christensen" air starting system is shown at 
Figs. 252 and 253. An air pump is driven by the engine, 
and this supplies air to an air reservoir or container 
attached to the fuselage. This container communicates 
with the top of an air distributor when a suitable control 
valve is open. An air pressure gauge is provided to 
enable one to ascertain the air pressure available. The 
top of each cylinder is provided with a check valve, 
through which air can flow only in one direction, i.e., from 
the tank to the interior of the cylinder. Under explosive 
pressure these check valves close. The function of the 
distributor is practically the same as that of an ignition 
timer, its purpose being to distribute the air to the cylin- 
ders of the engine only in the proper firing order. All 
the while that the engine is running and the car is in 
motion the air pump is functioning, unless thrown out of 
action by an easily manipulated automatic control. When 
it is desired to start the engine a starting valve is opened 
which permits the air to flow to the top of the distributor, 
and then through a pipe to the check valve on top of the 
cylinder about to explode. As the air is going through 
under considerable pressure it will move the piston down 
just ias the explosion would, and start the engine rotating. 
The inside of the distributor rotates and directs a charge 



Air- Starting System 



567 



of air to the cylinder next to fire. In this way the engine 
is given a number of revolutions, and finally a charge of 
gas will be ignited and the engine start off on its cycle of 
operation. To make starting positive and easier some 




MR PIPES 



Fig. 252. — Parts of Christensen Air Starting System Shown at A, and 
Application of Piping and Check Valves to Cylinders of Thomas- 
Morse Aeromotor Outlined at B. 



gasoline is injected in with the air so an inflammable mix- 
ture is present in the cylinders instead of air only. This 
ignites easily and the engine starts off sooner than would 
otherwise be the case. The air pressure required varies 
from 125 to 250 pounds per square inch, depending upon 
the size and type of the engine to be set in motion. 



568 



Aviation Engines 







•i-H 

1 

CO 

<M 

bb 



Electric Starting Systems 569 

ELECTRIC STARTING SYSTEMS 

Starters utilizing electric motors to turn over the 
engine have been recently developed, and when properly 
made and maintained in an efficient condition they an- 
swer all the requirements of an ideal starting device. 
The capacity is very high, as the motor may draAV cur- 
rent from a storage battery and keep the engine turning 
over for considerable time on a charge. The objection 
against their use is that it requires considerable compli- 
cated and costly apparatus which is difficult to under- 
stand and which requires the services of an expert electri- 
cian to repair should it get out of order, though if bat- 
tery ignition is used the generator takes the place of the 
usual ignition magneto. 

In the Delco system the electric current is generated 
by a combined motor-generator permanently geared to 
the engine. When the motor is running it turns the 
armature and the motor generator is acting as a dynamo, 
only supplying current to a storage battery. On account 
of the varying speeds of the generator, which are due to 
the fluctuation in engine speed, some form of automatic 
switch which will disconnect the generator from the bat- 
tery at such times that the motor speed is not sufficiently 
high to generate a current stronger than that delivered 
by the battery is needed. These automatic switches are 
the only delicate part of the entire apparatus, and while 
they require very delicate adjustment they seem to per- 
form very satisfactorily in practice. 

When it is desired to start the engine an electrical 
connection is established between the storage battery and 
the motor-generator unit, and this acts as a motor and 
turns the engine over by suitable gearing which engages 
the gear teeth cut into a special gear or disc attached to 
the engine crank-shaft. When the motor-generator fur- 
nishes current for ignition as well as for starting the 
motor, the fact that the current can be used for this work 
as well as starting justifies to a certain extent the rather 



570 Aviation Engines 

complicated mechanism which forms a complete starting 
and ignition system, and which may also be nsed for light- 
ing if necessary in night flying. 

An electric generator and motor do not complete a 
self-starting system, because some reservoir or container 
for electric current must be provided. The current from 
the generator is usually stored in a storage battery from 
which it can be made to return to the motor or to the 
same armature that produced it. The fundamental units 
of a self-starting system, therefore, are a generator to 
produce the electricity, a storage battery to serve as a 
reservoir, and an electric motor to rotate the motor crank- 
shaft. Generators are usually driven by enclosed gear- 
ing, though silent chains are used where the center dis- 
tance between the motor shaft and generator shaft is too 
great for the gears. An electric starter may be directly 
connected to the gasoline engine, as is the case where the 
combined motor-generator replaces the fly-wheel in an 
automobile engine. The motor may also drive the engine 
by means of a silent chain or by direct gear reduction. 

Every electric starter must use a switch of some kind 
for starting purposes and most systems include an out- 
put regulator and a reverse current cut-out. The output 
regulator is a simple device that regulates the strength 
of the generator current that is supplied the storage bat- 
tery. A reverse current cut-out is a form of check 
valve that prevents the storage battery from discharging 
through the generator. Brief mention is made of electric 
starting because such systems will undoubtedly be incor- 
porated in some future airplane designs. Battery igni- 
tion is already being experimented with. 



BATTERY IGNITION SYSTEM PARTS 

A battery ignition system in its simplest form consists 
of a current producer, usually a set of dry cells or a 
storage battery, an induction coil to transform the low 
tension current to one having sufficient strength to jump 



Battery Ignition System Parts 571 

the air gap at the spark-plug, an igniter member placed 
in the combustion chamber and a timer or mechanical 
switch operated by the engine so that the circuit will be 
closed only when it is desired to have a spark take place 
in the cylinders. Battery ignition systems may be of two 
forms, those in which the battery current is stepped up 
or intensified to enable it to jump an air gap between the 
points of the spark ping, these being called "high ten- 
sion" systems and the low tension form (never used on 
airplane motors) in which the battery current is not inten- 
sified to a great degree and a spark produced in the cylin- 
der by the action of a mechanical circuit breaker in the 
combustion chamber. The low tension system is the sim- 
plest electrically but the more complex mechanically. 
The high tension system has the fewest moving parts but 
numerous electrical devices. At the present time all air- 
plane engines use high tension ignition systems, the mag- 
neto being the most popular at the present time. The 
current distribution and timing devices used with modern 
battery systems are practically the same as similar parts 
of a magneto. 



INDEX 

A 

PAGE 

Action of Four-cycle Engine 38 

Action of Le Ehone Kotary Engine 503 

Action of Two-cycle Engine 41 

Action of Vacuum Feed System 119 

Actual Duration of Different Functions 93 

Actual Heat Efficiency 62 

Adiabatic Diagram 51 

Adiabatic Law 50 

Adjustment of Bearings 449 

Adjustment of Carburetors 151 

Aerial Motors, Must be Light 20 

Aerial Motors, Operating Conditions of 19 

Aerial Motors, Requirements of 19 

Aeromarine Six-cylinder Engine 527 

Aeronautics, Division in Branches 18 

Aerostatics 18 

Air-cooled Engine Design 229 

Air-cooling Advantages 231 

Air-cooling, Direct Method 228 

Air-cooling Disadvantages 231 

Air-cooling Systems 223- 

Aircraft, Heavier Than Air 17 

Aircraft, Lighter Than Air 18 

Aircraft Types, Brief Consideration of 17 

Air Needed to Burn Gasoline 113 

Airplane Engine, Power Needed 21 

Airplane Engines, Overhauling 412 

Airplane Engine, How to Time 269 

Airplane Engine Lubrication 209 

Airplane, How Supported 21 

Airplane Motors, German 543 

Airplane Motor Types 20 

Airplane Motors, Weight of 21 

Airplane Power Plant Installation 324 

Airplane Types 18 

Airplanes, Horse-power Used in 26 

Air Pressure Diminution, With Altitude 144 

Altitude, How it Affects Mixture 153 

Aluminum, Use in Pistons 297 

573 



574 



Index 



PAGE 

American Aviation Engines, Statistics 546 

Anzani Eadial Engine Installation 344 

Anzani Six-cylinder Star Engine 465 

Anzani Six-cylinder Water-cooled Engine 459 

Anzani Ten- and Twenty-cylinder Engines 468 

Anzani Three-cylinder Engine * 459 

Anzani Three-cylinder Y Type 462 

Argus Engine Construction 545 

Armature Windings 168 

Atmospheric Conditions, Compensating For 143 

Austro-Daimler Engine 557 

Aviatics 18 

Aviation Engine, Aeromarine 527 

Aviation Engine, Anzani Six-cylinder Star 465 

Aviation Engine, Canton and, Unne 469 

Aviation Engine Cooling 219 

Aviation Engine, Curtiss 519 

Aviation Engine Cylinders 233 

Aviation Engine, Early Gnome 472 

Aviation Engine, German Gnome Type 495 

Aviation Engine, Gnome Monosoupape 486 

Aviation Engine, How To Dismantle 415 

Aviation Engine, How to Start 460 

Aviation Engine, Le Ehone Eotary 495 

Aviation Engine Oiling 218 

Aviation Engine Parts, Functions of 82 

Aviation Engine, Renault Air-cooled 507 

Aviation Engine, Stand for Supporting 414 

Aviation Engine, Sturtevant 515 

Aviation Engine, Thomas-Morse • 521 

Aviation Engine Types 457 

Aviation Engine, Wisconsin 531 

Aviation Engines, Anzani Six-cylinder Water-cooled 459 

Aviation Engines, Anzani Ten- and Twenty-cylinder 468 

Aviation Engines, Anzani Three-cylinder 459 

Aviation Engines, Anzani Y Type 462 

Aviation Engines, Argus 545 

Aviation Engines, Austro-Daimler 557 

Aviation Engines, Benz 551 

Aviation Engines, Four- and Six-cylinder 88 

Aviation Engines, German 543 

Aviation Engines, Hall-Scott 539 

Aviation Engines, Hispana-Suiza 512 

Aviation Engines, Mercedes 543 

Aviation Engines, Overhauling 412 

Aviation Engines, Principal Parts of 80 

Aviation Engines, Starting Systems For 567 

Aviation Engines, Sunbeam , 558 



Index 515 

B 

PAGE 

Balanced Crank-shafts 318 

Ball-bearing Crank-shafts 319 

Battery Ignition Systems 571 

Baverey Compound Nozzle 137 

Bearings, Adjustment of : . 449 

Bearing Alignment 453 

Bearing Brasses, Fitting 450 

Bearing Parallelism, Testing 453 

Bearing Scrapers and Their Use 446 

Benz Aviation Engines 551 

Benz Engine Statistics 551 

Berling Magneto 174 

Berling Magneto, Adjustment of 180 

Berling Magneto Care 180 

Berling Magneto Circuits 176 

Berling Magneto, Setting 178 

Block Castings 234 

Blowing Back 269 

Bolts, Screwing Down 452 

Bore and Stroke Eatio 240 

Boyles Law 49 

Brayton Engine 48 

Breaker Box, Adjustment of 180 

Breast and Hand Drills 387 

Burning Out Carbon Deposits 421 

Bushings, Camshaft, Wear in 456 



C 

Calipers, Inside and Outside 398 

Cam Followers, Types of 260 

Cams for Valve Actuation 259 

Cam-shaft Bushings 456 

Cam-shaft Design 313 

Cam-shaft Drive Methods 261 

Cam-shaft Testing 451 

Cam-shafts and Timing Gears 456 

Canton and Unne Engine 469 

Carbon, Burning out with Oxygen 421 

Carbon Deposits, Cause of 418 

Carbon Removal 419 

Carbon Scrapers, How Used 420 

Carburetion Principles 112 

Carburetion System Troubles 355 

Carburetor, Claiulel 127 

Carburetor, Compound Nozzle Zenith 135 



576 



Index 



PAGE 

Carburetor, Concentric Float and Jet Type 125 

Carburetor, Duplex Zenith 138 

Carburetor, Duplex Zenith, Trouble in 357 

Carburetor Installation, In Airplanes 148 

Carburetor, Le Ehone 501 

Carburetor, Master Multiple Jet 133 

Carburetor, Schebler 125 

Carburetor Troubles, How to Locate 354 

Carburetor, Two Stage 131 

Carburetor, What it Should Do 114 

Carburetors, Float Feed 122 

Carburetors, Multiple Nozzle 130 

Carburetors, Notes on Adjustment 151 

Carburetors, Eeversing Position of 149 

Carburetors, Spraying • 120 

Care of Dixie Magneto 188 

Castor Oil, for Cylinder Lubrication 205 

Castor Oil, Why Used In Gnome Engines 211 

Center Gauge 403 

Chisels, Forms of 384 

Christensen Air Starting System 567 

Circuits, Magnetic 161 

Classification of Engines 458 

Claudel Carburetor 127 

Cleaning Distributor 180 

Clearances Between Valve Stem and Actuators 261 

Combustion Chamber Design 239 

Combustion Chambers, Spherical 76 

Common Tools, Outfit of 378 

Comparing Two-cycle and Four-cycle Types 44 

Compound Cam Followers 260 

Compound Piston Kings. 301 

Compressed Air Starting System 565 

Compression, Factors Limiting 69 

Compression, in Explosive Motors, Value of 68 

Compression Pressures, Chart for 72 

Compression Temperature 71 

Computations for Horse-power Needed 25 

Computations for Temperature 52 

Concentric Piston Eing 299 

Concentric Valves 255 

Connecting Eod Alignment, Testing 454 

Connecting Eod, Conventional 308 

Connecting Eod Forms 305 

Connecting Eod, Gnome Engine 305 

Connecting Eods, Fitting 449 

Connecting Eods for Vee Engines 310 

Connecting Eods, Le Ehone 498 



Index 577 

PAGE 

Connecting Rods, Master 310 

Constant Level Splash System 215 

Construction of Dixie Magneto 186 

Construction of Pistons 288 

Conversion of Heat to Power 58 

Cooling by Air 223 

Cooling by Positive Water Circulation 224 

Cooling, Heat Loss in 66 

Cooling System Defects 358 

Cooling Systems Used 223 

Cooling Systems, Why Needed 219 

Cotter Pin Pliers , 384 

Crank-case, Conventional 320 

Crank-case Forms 320 

Crank-case, Gnome •. 323 

Crank-shaft, Built Up 315 

Crank-shaft Construction 315 

Crank-shaft Design 315 

Crank-shaft Equalizer 449 

Crank-shaft Form 315 

Crank-shaft, Gnome Engine 483 

Crank-shafts, Balanced 318 

Crank-shafts, Ball Bearing 319 

Cross Level 403 

Crude Petroleum, Distillates of Ill 

Curtiss Aviation Engines 519 

Curtiss Engine Installation 328 

Curtiss Engine Eepairing Tools 408 

Cutting Oil Grooves 448 

Cylinder Blocks, Advantages of 237 

Cylinder Block, Duesenberg 235 

Cylinder Castings, Individual 234 

Cylinder Construction 233 

Cylinder Faults and Correction 416 

Cylinder Form and Crank-shaft Design 238 

Cylinder Head Packings 417 

Cylinder Head, Eemovable 239 

Cylinder, I Head Form 248 

Cylinder, L Head Form 248 

Cylinder Oils 206 

Cylinder Placing 20 

Cylinder Placing in V Motor 99 

Cylinder Retention, Gnome 475 

Cylinder, T Head Form 248 

Cylinders, Cast in Blocks 235 

Cylinders, Odd Number in Rotary Engines 482 

Cylinders, Repairing Scored 423 

Cylinders, Valve Location in 245 



578 



Index 



D 

PAGE 

Defects in Cylinders 417 

Defects in Dry Battery 373 

Defects in Fuel System 354 

Defects in Induction Coil 373 

Defects in Magneto 372 

Defects in Storage Battery 372 

Defects in Timer 373 

Defects in Wiring and Remedies 373 

Die Holder 394 

Dies for Thread Cutting 395 

Diesel Motor Cards 67 

Diesel System 144 

Direct Air Cooling 228 

Dirigible Balloons 18 

Dismantling Airplane Engine 415 

Distillates of Crude Petroleum ' Ill 

Division of Circle in Degrees 268 

Dixie Ignition Magneto 184 

Dixie Magneto, Care of 188 

Draining Oil From Crank-case 214 

Drilling Machines 386 

Drills, Types and Use 388 

Driving Cam-shaft, Methods of 262 

Dry Cell Battery, Defects in 373 

Duesenberg Sixteen Valve Engine 525 

Duesenberg Valve Action 255 

Duplex Zenith Carburetor 138 

E 

Early Gnome Motor, Construction of 472 

Early Ignition Systems 155 

Early Types of Gas Engine 28 

Early Vaporizer Forms 120 

Eccentric Piston Eing 299 

Economy, Factors Governing 64 

Efficiency, Actual Heat 62 

Efficiency, Maximum Theoretical 61 

Efficiency, Mechanical 62 

Efficiency of Internal Combustion Engine 60 

Efficiency, Various Measures of 61 

Eight-cylinder Engine 95 

Eight-cylinder Timing Diagram 276 

Electricity and Magnetism, Relation of 162 

Electrical Ignition Best 156 

Electric Starting Systems 569 

Engine, Advantages of V Type 95 



Index 579 

PAGE 

Engine Base Construction 319 

Engine Bearings, Adjusting 443 

Engine Bearings, Befitting 442 

Engine Bed Timbers, Standard 330 

Engine, Four-cycle, Action of 38 

Engine, Four-cycle, Piston Movements in 40 

Engine Functions, Duration of 93 

Engine Ignition, Locating Troubles 353 

Engine Installation, Gnome 344 

Engine Installation, Anzani Eadial . . . . „ 344 

Engine Installation, Hall-Scott 332 

Engine Installation, Eotary 342 

Engine Operation, Sequence of 84 

Engine Parts and Functions 80 

Engine Starts Hard, Ignition Troubles Causing 369 

Engine Stoppage, Causes of 347 

Engine Temperatures 221 

Engine Trouble Charts 369 

Engine Troubles, Cooling 358 

Engine Troubles, Hints For Locating 345 

Engine Troubles, Ignition 353 

Engine Troubles, Noisy Operation , 359 

Engine Troubles, Oiling 357 

Engine Troubles Summarized 350 

Engine, Two-cycle, Action of 41 

Engines, Classification of 458 

Engines, Cylinder Arrangement 31-32 

Engines, Eight-cylinder V 95 

Engines, Four-cylinder Forms 88 

Engines, Graphic Comparison of 33-34-35 

Engines, Internal Combustion, Types of 30 

Engines, Multiple Cylinder, Power Delivery in 91 

Engines, Multiple Cylinder, Why Best 83 

Engines, Eotary Cylinder 107 

Engines, Six-cylinder Forms 88 

Engines, Twelve-cylinder 96 

Equalizer, Crank-shaft 449 

Exhaust Closing 270 

Exhaust Valve Design, Early Gnome 475 

Exhaust Valve Opening 270 

Explosive Gases, Mixtures of 56 

Explosive Motors, Inefficiency in 74 

Explosive Motors, Why Best 27 

F 

Factors Governing Economy 64 

Eactors Limiting Compression 70 

Faults in Ignition 352 



580 



Index 



PAGE 

Figuring Horse-power Needed 21 

Piles, Use and Care of 383 

First Law of Gases 49 

Fitting Bearings By Scraping 447 

Fitting Brasses 450 

Fitting Connecting Rods 449 

Fitting Main Bearings 448 

Fitting Piston Rings 439 

Float Feed Carburetor Development 124 

Float .Feed Carburetors 122 

Force Feed Oiling System 218 

Forked Connecting Rods 310 

Four-cycle Engine, Action of 38 

Four-cycle Engine, Why Best 45 

Fourteen-cylinder Engine 474 

Four Valves Per Cylinder 284 

Friction, Definition of 302 

Fuel Feed By Gravity , 116 

Fuel Feed by Vacuum Tank 117 

Fuel Storage and Supply 116 

Fuel Strainers, Types of 141 

Fuel Strainers, Utility of 140 

Fuel System Faults 354 

Fuel System Installation, Hall-Scott 336 

Fuel System, Gnome 490 

Fuel Utilization Chart 62 

G 

Gas Engine, Beau de Rocha '3 Principles 59 

Gas Engine Development 28 

Gas Engine, Early Forms of • 48 

Gas Engine, Inventors of 29 

Gas Engine, Theory of 47 

Gases, Compression of 49 

Gases, First Law of 49 

Gases, Second Law of 50 

Gaskets, How to Use 452 

Gasoline, Air Needed to Burn 113 

Gas Engines, Parts of 80 

Gas Vacuum Engine, Brown 's 28 

German Airplane Motors 543 

German Gnome Type Engine 495 

Gnome Aviation Engine, Early Form 472 

Gnome Crank-shaft 483 

Gnome Cylinder, Machining 489 

Gnome Cylinder Retention 475 

Gnome Engine, Fuel^ Lubrication and Ignition 490 



Index 581 

PAGE 

Gnome Engine, German Type 495 

Gnome Engine Installation 344 

Gnome Firing Order 482 

Gnome Fourteen-Cylinder Engine 474 

Gnome Fourteen-cylinder Engine Details 480 

Gnome Monosoupape, How to Time 278 

Gnome Monosoupape Type Engine 486 

Graphic Comparison of Engine Types 33-34-35 

Graphic Comparison, Two- and Four-cycle 46 

Gravity Feed System 116 

Grinding Valves 429 



H 

Hall-Scott Aviation Engines 539 

Hall-Scott Engine Installation 332 

Hall-Scott Engine, Preparations For Starting 341 

Hall-Scott Engine- Tools 410 

Hall-Scott Lubrication System 211 

Hall-Scott Statistic Sheet 544 

Heat and Its Work 54 

Heat in Gas Engine Cylinder 69 

Heat Given to Cooling Water 78 

Heat Loss, Causes of 74 

Heat Loss in Airplane" Engine 221 

Heat Loss in Wall Cooling 65 

High Altitude, How it Affects Power 144 

High Tension Magneto 172 

Hints For Locating Engine Troubles 345 

Hints for Starting Engine 361 

Hispana-Suiza Model A Engine 512 

Horse-power Needed in Airplane 21 

Horse-power Needed, How Figured 22 

How An Engine is Timed 277 



I 

Ignition, Electric 156 

Ignition, Elements of 157 

Ignition of Gnome Engine 490 

Ignition System, Battery 571 

Ignition Systems, Early 155 

Ignition System Faults 352 

Ignition, Time of 273 

Ignition, Two Spark 196 

I Head Cylinders 248 

Improvements in Gas Engines 29 

Indicating Meters, Engine Speed 563 



582 Index 

PAGE 

Indicating Meters, Oil and Air Pressure 563 

Indicator Cards, How To Eead 66 

Indicator Cards, Value of 66 

Individual Cylinder Castings 234 

Induction Coil, Defects in 373 

Inefficiency, Causes of 74 

Inlet Valve Closing 272 

Inlet Valve Opening 270 

Installation, Airplane Engine 324 

Installation, Curtiss OX 2 Engine 328 

Installation, Hall-Scott Engine 332 

Installation of Eotary Engines 342 

Intake Manifold Construction 143 

Intake Manifold Design 142 

Internal Combustion Engine, Efficiency of 60, 62 

Internal Combustion Engines, Main Types of 30 

Inverted Engine Placing 325 

Isothermal Diagram 51 

Isothermal Law 48 



K 

Keeping Oil Out of Combustion Chamber 303 

Knight Sleeve Valves 266 



L 

Lag and Lead, Explanation of 268 

Lapping Crank-pins 445 

Lead Given Exhaust Valve 270 

Leak Proof Piston Eings 301 

Lenoir Engine Action 48 

Le Ehone Cams and Valve Actuation 500 

Le Ehone Carburetor 501 

Le Ehone Connecting Eod Assembly, Distinctive 498 

Le Ehone Engine Action 503 

Le Ehone Eotary Engine 495 

L Head Cylinders 248 

Liquid Fuels, Properties of 110 

Locating Carburetor Troubles 354 

Locating Engine Troubles , 350 

Locating Ignition Troubles 353 

Locating Oiling Troubles 357 

Location of Magneto Trouble 181 

Losses in Wall Cooling 65 

Lost Power and Overheating, Summary of Troubles Causing 363 

Lubricants, Derivation of 204 

Lubricants, Eequirements of ' 204 

t 



Index 583 

PAGE 

Lubricating System Classification 208 

Lubricating Systems, Selection of 208 

Lubrication By Constant Level Splash System 215 

Lubrication By Dry Crank-case Method 218 

Lubrication By Force Feed Best 218 

Lubrication of Magneto 180 

Lubrication System, Gnome 490 

Lubrication System, Hall-Scott 211 

Lubrication System, Thomas-Morse 210 

Lubrication, Theory of 202 

Lubrication, Why Necessary 201 



M 

Magnetic Circuits 161 

Magnetic Influence Defined " 158 

Magnetic Lines of Force 161 

Magnetic Substances 158 

Magnetism, Flow Through Armature , 166 

Magnetism, Fundamentals of 157 

Magnetism, Eelation to Electricity 162 

Magneto, Action of High Tension 173 

Magneto Armature Windings 168 

Magneto, Basic Principles of 163 

Magneto", Berling 174 

Magneto, Defects in 372 

Magneto Distributor, Cleaning 180 

Magneto Ignition Systems 169 

Magneto Ignition Wiring 179 

Magneto Interrupter, Adjustment of 180 

Magneto, Low Voltage 168 

Magneto, Lubrication of 180 

Magneto Maintenance 180 

Magneto, Method of Driving 175 

Magneto Parts' and Functions 167 

Magneto, The Dixie , . 184 

Magneto Timing 179 

Magneto, Timing Dixie 188 

Magneto, Transformer System 171 

Magneto Trouble, Location of 181 

Magneto, True High Tension 172 

Magneto, Two Spark Dual 177 

Magnets, Forms of 160 

Magnets, How Produced 162 

Magnets, Properties of 159 

Main Bearings, Fitting 448 

Manifold, iDtake 143 

Master Multiple Jet Carburetor 133 



584 



Index 



PAGE 

Master Rod Construction 310 

Maximum Theoretical Efficiency 61 

Meaning of Piston Speed 241 

Measures of Efficiency 61 

Measuring Tools 397 

Mechanical Efficiency 62 

Mercedes Aviation Engine 543 

Metering Pin Carburetor, Stewart 128 

Micrometer Caliper, Reading 405 

Micrometer Calipers, Types and Use 404 

Mixture, Effect of Altitude on 153 

Mixture, Proportions of 151 

Mixture, Starvation of 149 

Monosoupape Gnome Engine 486 

Mother Rod, Gnome Engine 305 

Motor Misfires, Carburetor Faults Causing 374 

Motor Misfires, Ignition Troubles Causing 370 

Motor Races, Carburetor Faults Causing 374 

Motor Starts Hard, Carburetor Faults Causing 374 

Motor Stops In Flight, Carburetor Faults 374 

Motor Stops Without Warning, Ignition Troubles 370 

Multiple Cylinder Engine, Why Best 83 

Multiple Nozzle Vaporizers 129 

Multiple Valve Advantages 286 

N 

Noisy Engine Operation, Causes of 359 

Noisy Operation, Carburetor Faults Causing 374 

Noisy Operation, Summary of Troubles Causing 365 

O 

Off-set Cylinders, Reason for 243 

Oil Bi-pass, Function of 213 

Oil, Draining From Crank-ease 214 

Oil Grooves, Cutting 448 

Oil Pressure in Hall-Scott System 214 

Oil Pressure Relief Bi-pass 213 

Oiling System Defects 357 

Oils for Cylinder Lubrication 206 

Oils for Hall-Scott Engine 215 

Oils for Lubrication 204 

Operating Principles of Engines 37 

Oscillating Piston Pin 295 

Otto Four-cycle Cards 67 

Overhauling Aviation Engines 412 

Overhead Cam-shaft Location 252 

Overheating, Causes of 359 



Index 585 

p 

PAGE 

Panhard Concentric Valves 255 

Petroleum, Distillates of Ill 

Piston, Differential 291 

Piston Pin Eetention 293 

Piston Eing Construction 298 

Piston Eing Joints 299 

Piston Eing Manipulation 438 

Piston Eing Troubles 437 

Piston Eings, Compound 301 

Piston Eings, Concentric 299 

Piston Eings, Eccentric , . 299 

Piston Eings, Fitting 439 

Piston Eings, Leak Proof 301 

Piston Eings, Eeplacing 441 

Piston Speed in Airplane Engines 241 

Piston Speed, Meaning of 241 

Piston Troubles and Eemedies 436 

Pistons, Aluminum 296 

Pistons, Details of 288 

Pistons for Two-cycle Engines 289 

.Positive Valve Systems 283 

Power, Affected by High Altitude 145 

Power Delivery in Multiple Cylinder Engines 91 

Power, How Obtained From Heat 58 

Power Needed in Airplane Engines 21 

Power Used in Airplanes 26* 

Precautions in Assembling Parts 452 

Pressure Eelief Fitting 213 

Pressures and Temperatures 63 

Principles of Carburetion 112 

Principles of Magneto Action 163 

Properties of Cylinder Oils 207 

Properties of Liquid Fuels 110 

Pump Circulation Systems 226 

Pump Forms 226 

R 

Eadial Cylinder Arrangement 103 

Eeading Indicator Cards 67 

Eeamers, Types and Use 392 

Eeassembling Parts, Precautions in 451 

Eemovable Cylinder Head 239 

Eenault Air Cooled Engine 507 

Eenault Engine Details 508 

Eepairing Scored Cylinders 423 

Requisites for Best Power Effect 59 



586 Index 

PAGE 

Reseating and Truing Valves 426 

Resistance, Influence of 22 

Rotary Cylinder Engines 107 

Rotary Engine, Le Rhone 495. 

Rotary Engines, Castor Oil for 211 

Rotary Engines, Installing 342 

Rotary Engines, Why Odd Number of Cylinders 109 

Rotary Engines, Why Odd Number of Cylinders Is Used 482 



S. A. E. Engine Bed Dimensions 330 

Salmson Nine-cylinder Engine 470 

Scissors Joint Rods 310 

Scored Cylinders, Repairing 422 

Scrapers, Types of Bearing 446 

Scraping Bearings to Fit 447 

Second Law of Gases 50 

Sequence of Engine Operation 84 

Shebler Carburetor 125 

Six-cylinder Timing Diagram 275 

Sixteen Valve Duesenberg Engine 525 

Skipping or Irregular Operation, Causes of 367 

Sliding Sleeve Valves 266 

Spark Plug Air Gaps, Setting 197 

Spark Plug, Design of 193 

Spark Plug, Mica 194 

Spark Plug, Porcelain 193 

Spark Plugs, Defects in 371 

Spark Plugs for Two Spark Ignition 197 

Spark Plug, Special for Airplane Engine 199 

Spark Plug, Standard S. A. E 195 

Spherical Combustion Chambers 76 

Splash Lubrication 215 

Split Pin Remover 384 

Spraying Carburetors 120 

Springless Valves 280 

Springs, for Valves 263 

Spring Winder 384 

Sprung Cam-shaft, Testing 451 

Stand for Supporting Engine 414 

Starting Engine, Hints for 361 

Starting Hall-Scott Engine 341 

Starting System, Christensen 567 

Starting Systems, Compressed Air 565 

Starting Systems, Electric 569 

Statistics, American Engines 546, 547 

Statistic Sheet, Hall-Scott Engines 544 






Index 587 

PAGE 

Statistics of Benz Engine 551 

Steam Engine, Efficiency of 59 

Steam Engine, Why Not Used 27 

Steel Scale, Machinists' 399 

Stewart Metering Pin Carburetor 128 

Storage Battery, Defects in 372 

Stroke and Bore Ratio 240 

Sturtevant Model 5A Engine 515 

Summary of Engine Types 30 

Sunbeam Aviation Engines 588 

Sunbeam Eighteen-Cylinder Engine 561 



T 

Tap and Die Sets 397 

Taps for Thread Cutting 394 

Tee Head Cylinders 247 

Temperature Computations 52 

Temperatures and Explosive Pressures 64 

Temperatures and Pressures 63 

Temperatures, Operating 221 

Testing Bearing Parallelism 453 

Testing Connecting Eod Alignment 454 

Testing Fit of Bearings 446 

Testing Sprung Cam-shaft 451 

Theory of Gas Engine 47 

Theory of Lubrication 203 

Thermo-syphon Cooling System 227 

Thomas-Morse Aviation Engine 521 

Thomas-Morse Lubrication System 210 

Thread Pitch Gauge 403 

Time of Ignition 273 

Timer, Defects in 373 

Times of Explosion 56 

Timing Dixie Magneto 188 

Timing Gears, Effects of Wear 456 

Timing Magneto 179 

Timing Valves 267 

Tool Outfits, Typical 408 

Tools for Adjusting and Erecting 378 

Tools for Bearing Work 445 

Tools for Curtiss Engines 408 

Tools for Grinding Valves 430 

Tools for Hall-Scott Engines 410, 411 

Tools for Measuring 397 

Tools for Reseating Valves 426 

Trouble in Carburetion System 355 

Trouble, Location of Magneto 181 



588 Index 

PAGE 

Troubles, Engine, How to Locate 345 

Troubles, Ignition 353 

Troubles in Oiling System 357 

True High Tension Magneto .• 172 

Twelve-Cylinder Engines 96 

Two- and Four-Cycle Types, Comparison of 44 

Two-Cycle Engine Action 41 

Two-Cycle Three-Port Engine 43 

Two-Cycle Two-Port Engine 42 

Two-Spark Ignition 196 

Two-Stage Carburetor 131 

Types of Aircraft 17 

Types of Internal Combustion Engines 30 



V 

Vacuum Fuel Feed, Stewart 119 

Value of Compression 69 

Value of Indicator Cards 66 

Valve Actuation, Le Ehone 500 

Valve Design and Construction 256 

Valve-Grinding Processes 429 

Valve-Lifting Cams 259 

Valve-Lifting Plungers 260 

Valve Location Practice 245 

Valve Operating Means 252 

Valve Operating System, Depreciation in 433 

Valve Operation 258 

Valve Removal and Inspection 424 

Valve Seating, How to Test 432 

Valve Springs . ■ 263 

Valve Timing, Exhaust 270 

Valve Timing, Gnome Monosoupape 278 

Valve Timing, Intake 270 

Valve Timing, Lag and Lead 269 

Valve Timing Proceedure 277 

Valve Timing Practice 267 

Valves, Electric Welded 258 

Valves, Flat and Bevel Seat 257 

Valves, Four per Cylinder 284 

Valves, How Placed in Cylinder 247 

Valves in Cages 249 

Valves in Removable Heads 249 

Valves, Materials Used for 258 

Valves, Reseating 426 

Vaporizer, Simple Forms of 120 

V Engines, Cylinder Arrangement in 102 

Vernier, How Used 401 



Index 589 

w 

PAGE 

Wall Cooling, Losses in „ . . . , 65 

Water Cooling by Natural Circulation 227 

Water Cooling System 224 

Weight of Airplane Motors 21 

Wiring, Defects in 373 

Wiring Magneto Ignition System 179 

Wisconsin Engines 531 

Wrenches, Forms of 380 

Wristpin Retention 293 

Wristpin Retention Locks 295 

Wristpin Wear and Remedy 442 

Z 

Zenith Carburetor, Action of 137 

Zenith Duplex Carburetor, Troubles in 356 

Zenith Carburetor Installation „ 139 



I 



CATALOGUE 

Of the LATEST and BEST 

PRACTICAL and MECHANICAL 

BOOKS 

Including Automobile and Aviation Books 




Any of these books will be sent prepaid to any part of the world, 

on receipt of price. Remit by Draft, Postal Order, Express 

Order or Registered Letter 



Published and For Sale By 

The Norman W. Henley Publishing Co., 

2 West 45th Street, New York, U.S.A. 



THE NORMAN W. HENLEY PUBLISHING CO 



INDEX 



PAGES 

Air Brakes 21, 24 

Arithmetic 14, 25, 31 

Automobile Books 3, 4, 5, 6 

Automobile Charts 6, 7 

Automobile Ignition Systems 5 

Automobile Lighting 5 

Automobile Questions and Answers 4 

Automobile Repairing 4 

Automobile Starting Systems 5 

Automobile Trouble Charts 5, 6 

Automobile Welding 5 

Aviation 7 

Aviation Chart 7 

Batteries, Storage 5 

Bevel Gear 19 

Boiler-Room Chart 9 

Brazing 7 

Cams 19 

Carburetion Trouble Chart 6 

Change Gear 19 

Charts 6, 7, 8 

Coal 22 

Coke.... 9 

Combustion 22 

Compressed Air 10 

Concrete 10, 11, 12 

Concrete for Farm Use 11 

Concrete for Shop Use 11 

Cosmetics 27 

Cycleears 5 

Dictionary 12 

Dies 12, 13 

Drawing 13, 14 

Drawing for Plumbers 28 

Drop Forging 13 

Dynamo Building 14 

Electric Bells 14 

Electric Switchboards 14, 16 

Electric Tov Making 15 

Electric Wiring 14, 15, 16 

Electricity 14, 15, 16, 17 

Encyclopedia 24 

E-T Air Brake. 24 

Every-day Engineering 34 

Factory Management 17 

Ford Automobile 3 

Ford Trouble Chart 6 

Formulas and Recipes 29 

Fuel 17 

Gas Construction 18 

Gas Engines 18,19 

Gas Tractor 33 

Gearing and Cams 19 

Glossary of Aviation Terms 7, 12 

Heating 31, 32 

Horse-Power Chart 9 

Hot-Water Heating 31, 32 

House Wiring 15, 17 

How to Run an Automobile 3 

Hydraulics 5 

Ice and Refrigeration 20 

Ignition Systems • 5 

Ignition-Trouble Chart 6 

India Rubber 30 

Interchangeable Manufacturing 24 

Inventions 20 

Knots 20 

Lathe Work 20 



PAGES 

Link Motions 22 

Liquid Air 21 

Locomotive Boilers 22 

Locomotive Breakdowns 22 

Locomotive Engineering 21, 22, 23, 24 

Machinist Book 24, 25, 26 

Magazine, Mechanical 34 

Manual Training 26 

Marine Engineering 26 

Marine Gasoline Engines 19 

Mechanical Drawing 13, 14 

Mechanical Magazine 34 

Mechanical Movements 25 

Metal Work 12, 13 

Motorcycles 5,6 

Patents 20 

Pattern Making 27 

Perfumery 27 

Perspective 13 

Plumbing 28, 29 

Producer Gas 19 

Punches 13 

Questions and Answers on Automobile 4 

Questions on Heating 32 

Rai'road Accidents 23 

Railroad Charts 9 

Recipe Book 29 

Refrigeration 20 

Repairing Automobiles 4 

Rope Work 20 

Rubber 30 

Rubber Stamps 30 

Saw Filing 30 

Saws, Management of 30 

Sheet-Metal Works 12, 13 

Shop Construction 25 

Shop Management 25 

Shop Practice 25 

Shop Tools 25 

Sketching Paper 14 

Soldering 7 

Splices and Rope Work 20 

Steam Engineering 30, 31 

Steam Heating 31, 32 

Steel 32 

Storage Batteries . 5 

Submarine Chart 9 

Switchboards 14, 16 

Tapers 21 

Telegraphy, Wireless 17 

Telephone 16 

Thread Cutting 26 

Tool Making 24 

Toy Making 15 

Train Rules 23 

Tractive Power Chart 9 

Tractor, Gas 33 

Turbines 33 

Vacuum Heating 32 

Valve Setting 22 

Ventilation 31 

Watch Making 33 

Waterproofing 12 

Welding with Oxy-acetylene Flame 5, 33 

Wireless Telegraphy 17 

Wiring 14, 15 

Wiring Diagrams 14 



Any of these books promptly sent prepaid to any address in 
the world on receipt of price. 



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CATALOGUE OF GOOD, PRACTICAL BOOKS 



AUTOMOBILES AND MOTORCYCLES 

The Modern Gasoline Automobile — Its Design, Construction, and Opera- 
tion, 1918 Edition. By Victor W. Page, M.S.A.E. 

This is the most complete, practical and up-to-date treatise on gasoline automobiles and their 
component parts ever published. In the new revised and enlarged 1918 edition, all phases of 
automobile construction, operation and maintenance are fully and completely described, and 
in language anyone can understand. Every part of all types of automobiles, from light cycle- 
cars to heavy motor trucks and tractors, are described in a thorough manner, not only 
the automobile, but every item of it; equipment, accessories, tools needed, supplies and spare 
parts necessary for its upkeep, are fully discussed. 

It is clearly and concisely written by an expert familiar with every branch of the automobile industry 
and the originator of the practical system of self-education on technical subjects. It is a liberal edu- 
cation in the automobile art, useful to all who motor for either business or pleasure. 
Anyone reading the incomparable treatise is in touch with all improvements that have been 
made in motor-car construction. All latest developments, such as high speed aluminum motors 
and multiple valve and sleeve-valve engines, are considered in detail. ■ The latest ignition, 
carburetor and lubrication practice is outlined. New forms of change speed gears, and final 
power transmission systems, and all latest chassis improvements are shown and described. 
This book is used in all leading automobile schools and is conceded to be the Standard 
Treatise. The chapter on Starting and Lighting Systems has been greatly enlarged, and 
many automobile engineering features that have long puzzled laymen are explained so clearly 
that the underlying principles can be understood by anyone. This book was first published 
six years ago and so much new matter has been added that it is nearly twice its original size. 
The only treatise covering various forms of war automobiles and recent developments in motor- 
truckldesign as well as pleasure cars. This book is not too technical for the layman nor too elementary 
for the more expert. It is an incomparable work of reference for home or school. 1,000 6x9 pages, 
nearly 1,000 illustrations, 12 folding plates. Cloth bound. Price $3.00 

WHAT IS SAID OF THIS BOOK: 

"It is the best book on the Automobile seen up to date." — J. H. Pile, Associate Editor Auto- 
mobile Trade Journal. 

"Every Automobile Owner has use for a book of this character." — The Tradesman. 
"This book is superior to any treatise heretofore published on the subject." — The Inventive Age. 
" We know of no other volume that is so complete in all its departments, and in which the wide 
field of automobile construction with its mechanical intricacies is so plainly handled, both in 
the text and in the matter of illustrations." — The Motorist. 

"The book is very thorough, a careful examination failing to disclose any point in connection 
with the automobile, its care and repair, to have been overlooked." — Iron Age. 
" Mr. Page has done a great work, and benefit to the Automobile Field." — W. C. Hasford, 
Mgr. Y. M. C. A. Automobile School, Boston, Mass. 

" It is just the kind of a book a motorist needs if he wants to understand his car." — American 
Thresherman. 



The Model T Ford Car, Its Construction, Operation and Repair. By Victor 
W. Page, M.S.A.E. 

This is a complete instruction book. All parts of the Ford Model T Car are described and 
illustrated; the construction is fully described and operating principles made clear to everyone. 
Every Ford owner needs this practical book. You don't have to guess about the construction 
or where the trouble is, as it shows how to take all parts apart and how to locate and fix all 
faults. The writer, Mr. Page\ has operated a Ford car for many years and writes from actual 
knowledge. Among the contents are: 1. The Ford Car: Its Parts and Their Functions. 
2. The Engine and Auxiliary Groups. How the Engine Works — The Fuel Supply System — 
The Carburetor — Making the Ignition Spark — Cooling and Lubrication. 3. Details of Chassis. 
Change Speed Gear — Power Transmission — Differential Gear Action — Steering Gear — Front 
Axle — Frame and Springs — Brakes. 4. How to Drive and Care for the Ford. The Control 
System Explained — Starting the Motor — Driving the Car — Locating Roadside Troubles — 
Tire Repairs — Oiling the Chassis — Winter Care of Car. 5. Systematic Location of Troubles 
and Remedies. Faults in Engine — Faults in Carburetor — Ignition Troubles — Cooling and 
Lubrication System Defects — Adjustment of Transmission Gear — General Chassis Repairs. 
95 illustrations, 300 pages, 2 large folding plates. Price $1 .00 



How to Run an Automobile. By Victor W. Page, M.S.A.E. 

This treatise gives concise instructions for starting and running all makes of gasoline auto- 
mobiles, how to care for them, and gives distinctive features of control. Describes every 
step for shifting gears, controlling engines, etc. Among the chapters contained are: I. — 
Automobile Parts and Their Functions. II. — General Starting and Driving Instructions. 
III. — Typical 1917 Control Systems. IV. — Care of Automobiles. 178 pages. 72 specially 
made illustrations. Price SI. 00 



THE NORMAN W. HENLEY PUBLISHING CO 



Automobile Repairing Made Easy. By Victor W. Page, M.S.A.E. 

A comprehensive, practical exposition of every phase of modern automobile repairing prac- 
tice. Outlines every process incidental to motor car restoration. Gives plans for workshop 
construction, suggestions for equipment, power needed, machinery and tools necessarv to 
carry on business successfully. Tells how to overhaul and repair all parts of all auto- 
mobiles. Everything is explained so simpy that motorists and students can acquire a full 
working knowledge of automobile repairing. This work starts with the engine, then considers 
carburetion, ignition, cooling and lubrication systems. The clutch, change speed gearing 
and transmission system are considered in detail. Contains instructions for repairing all 
types of axles, steering gears and other chassis parts. Many tables, short cuts in figuring 
and rules of practice are given for the mechanic. Explains fully valve and magneto timing, 
'tuning" engines, systematic location of trouble, repair of ball and roller bearings, shop kinks! 
first aid to injured and a multitude of subjects of interest to all in the garage and repair business. 
This book contains special instructions on electric starting, lighting and ignition systems, tire 
repairing and rebuilding, autogenous welding, brazing and soldering, heat treatment of steel, latest 
timing practice, eight and twelve-cylinder motors, etc. 5%x8. Cloth. 1,056 pages, 1,000 illus- 
trations, 11 folding plates. Price . $3.00 

WHAT IS SAID OF THIS BOOK: 

'"Automobile Repairing Made Easy' is the best book on the subject I have ever seen and 
the only book I ever saw that is of any value in a garage." — Fred Jeffrey, Martinsburg, Neb. 
"I wish to thank you for sending me a copy of 'Automobile Repairing Made Easy.' I do 
not think it could be excelled." — S. W. Gisriel, Director of Instruction, Y. M. C. A., Phila- 
delphia, Pa. 



Questions and Answers Relating to Modern Automobile Construction, 
Driving and Repair. By Victor W. Page, M.S.A.E. 

A practical self-instructor for students, mechanics and motorists, consisting of thirty-seven 
lessons in the form of questions and answers, written with special reference to the require- 
ments of the non-technical reader desiring easily understood, explanatory matter relating 
to all branches of automobiling. The subject-matter is absolutely correct and explained in 
simple language. If you can't answer all of the following questions, you need this work. The 
answers to these and over 2,000 more are to be found in its pages. Give the name of all im- 
portant parts of an automobile and describe their functions. Describe action of latest types 
of kerosene carburetors. What is the difference between a "double" ignition system and a 
"dual" ignition system? Name parts of an induction coil. How are valves t-imed? What 
is an electric motor starter and how does it work? What are advantages of worm drive gear- 
ing? Name all important types of ball and roller bearings. What is a "three-quarter" float- 
ing axle: What is a two-speed axle? What is the Vulcan electric gear shift? Name the causes 
of lost power in automobiles. Describe all noises due to deranged mechanism and give causes; 
How can you adjust a carburetor by the color of the exhaust gases? What causes "popping" 
in the carburetor? What tools and supplies are needed to equip a car? How do you drive 
various makes of cars? What is a differential lock and where is it used? Name different 
systems of wire wheel construction, etc., etc. A popular work at a popular price. 5Mx7J^. 
Cloth. 650 pages, 350 illustrations, 3 folding plates. Price ..... $1.50 

WHAT IS SAID OF THIS BOOK: 

"If you own a car — get this book." — The Glassworker. 

"Mr. Page has the faculty of making difficult subjects plain and understandable." — Bristol 

Press. 

"We can name no writer better qualified to prepare a book of instruction on automobiles 

than Mr. Victor W. PageV' — Scientific American. 

"The best automobile catechism that has appeared." — Automobile Topics. 

"There are few men, even with long experience, who will not find this book useful. Great 

pains have been taken to make it accurate. Special recommendation must be given to the 

illustrations, which have been made specially for the work. Such excellent books as this 

greatly assist in fully understanding your automobile." — Engineering News. 



The Automobilist's Pocket Companion and Expense Record. Arranged by 
Victor W. Page, M.S.A.E. 

This book is not only valuable as a convenient cost record but contains much information of value 
to motorists. Includes a condensed digest of auto laws of all States, a lubrication schedule, 
hints for care of storage battery and care of tires, location of road troubles, anti-freezing 
solutions, horse-power table, driving hints and many useful tables and recipes of interest to 
all motorists. Not a technical book in any sense of the word, just a collection of practical 
facts in simple language for the everyday motorist. Price . . . . . $1.00 



CATALOGUE OF GOOD, PRACTICAL BOOKS 5 

Modern Starting, Lighting and Ignition Systems. By Victor W. Page, ALE. 

This practical volume has been written with special reference to the requirements of the non- 
technical reader desiring easily understood, explanatory matter, relating to all types of auto- 
mobile ignition, starting and lighting systems. It can be understood by anyone, even without 
electrical knowledge, because elementary electrical principles are considered before any at- 
tempt is made to discuss features of the various systems. These basic principles are clearly 
stated and illustrated with simple diagrams. All the leading systems of starting, lighting and 
ignition have been described and illustrated with the co-operation of the experts employed by the 
manufacturers. Wiring diagrams are shown in both technical and non-technical forms. All 
symbols are fully explained. It is a comprehensive review of modern starting and ignition 
system practice, and includes a complete exposition of storage battery construction, care and 
repair. All types of starting motors, generators, magnetos, and all ignition or lighting system- 
units are fully explained. Every person in the automobile business needs this volume. Among 
some of the subjects treated are: I. — Elementary Electricity; Current Production; Flow; 
Circuits; Measurements; Definitions; Magnetism; BatteryAction;GeneratorAction. II. — Battery 
Ignition Systems. III. — Magneto Ignition Systems. IV. — Elementary Exposition of Starting 
System Principles. V. — Typical Starting and Lighting Systems; Practical Application; Wiring 
Diagrams; Auto-lite, Bijur, Delco, Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse, 
Bosch-Rushmore, Genemotor, North-East, etc. VI. — Locating and Repairing Troubles in Start- 
ing and Lighting Systems. VII. — Auxiliary. Electric Systems; Gear-shifting by Electricity; 
Warning Signals; Electric Brake; Entz-Transmission, Wagner-Saxon Circuits, Wagner- 
Studebaker Circuits. 5^x73^. Cloth. 530 pages, 297 illustrations, 3 folding plates. 
Price $1.50 



Automobile Welding With the Oxy- Acetylene Flame. By M. Keith Dunham. 

This is the only complete book on the "why" and "how" of Welding with the Oxy-Acetylene 
Flame, and from its pages one can gain information so that he can weld anything that comes 
along. 

No one can afford to be without this concise book, as it first explains the apparatus to be 
used, and then covers in detail the actual welding of all automobile parts. The welding of 
aluminum, cast iron, steel, copper, brass and malleable iron is clearly explained, as well 
as the proper way to burn the carbon out of the combustion head of the motor. Among the 
contents are: Chapter I. — Apparatus Knowledge. Chapter II. — Shop Equipment and 
Initial Procedure. Chapter III. — Cast Iron. Chapter IV. — Aluminum. Chapter V. — ■ 
Steel. Chapter VI. — Malleable Iron, Copper, Brass, Bronze. Chapter VII. — Carbon Burn- 
ing and other Uses of Oxygen and Acetylene. Chapter VIII. — How to Figure Cost of Weld- 
ing. 167 pages, fully illustrated. Price $1.00 



Storage Batteries Simplified. By Victor W. Page, M.S.A.E. 

A comprehensive treatise devoted entirely to secondary batteries and their maintenance, 
repair and use. 

This is the most up-to-date book on this subject. Describes fully the Exide, Edison, Gould, 
Willard, U. S. L. and other storage battery forms in the types best suited for automobile, 
stationary and marine work. Nothing of importance has been omitted that the reader should 
know about the practical operation and care of storage batteries. No details have been 
slighted. The instructions for charging and care have been made as simple as possible. Brief 
Synopsis of Chapters: Chapter I. — Storage Battery Development; Types of Storage Bat- 
teries; Lead Plate Types; The Edison Cell. Chapter II. — Storage Battery Construction; 
Plates and Girds; Plante Plates; Faure Plates; Non-Lead Plates; Commercial Battery 
Designs. Chapter III. — Charging Methods; Rectifiers; Converters; Rheostats; Rules 
for Charging. Chapter IV. — Battery Repairs and Maintenance. Chapter V. — Industrial 
Application of Storage Batteries; Glossary of Storage Battery Terms. 208 Pages. Very 
Fully Illustrated. Price $1.50 net. 



Motorcycles, Side Cars and Cyclecars; their Construction, Management 
and Repair. By Victor W. Pag£, M.S.A.E. 

The only complete work published for the motorcyclist and cyclecarist. Describes fully all 
leading types of machines, their design, construction, maintenance, operation and repair. 
This treatise outlines fully the operation of two- and four-cycle power plants and all ignition, 
carburet ion and lubrication systems in detail. Describes all representative types of free 
engine clutches, variable speed gears and power transmission systems. Gives complete in- 
structions for operating and repairing all types. Considers fully electric self-starting and 
lighting systems, all types of spring frames and spring forks and shows leading control methods. 
For those desiring technical information a complete series of tables and many formula? to 
assist in designing are included. The work tells how to figure power needed to climb grades, 
overcome air resistance and attain high speeds. It shows how to select gear ratios for various 
weights and powers, how to figure braking efficiency required, gives sizes of belts and chains 
to transmit power safely, and shows how to design sprockets, belt pulleys, etc. This work 
also includes complete formula for figuring horse-power, shows how dynamometer tests are 



THE NORMAN W. HENLEY PUBLISHING CO. 



made, defines relative efficiency of air and water-cooled engines, plain and anti-friction bear- 
ings and many other data of a practical, helpful, engineering nature. Remember that you 
get this information in addition to the practical description and instructions which alone are 
worth several times the price of the book. 550 pages. 350 specially made illustrations, 5 
folding plates. Cloth. Price $1.50 

WHAT IS SAID OF THIS BOOK: 

"Here is a book that should be in the cycle repairer's kit." — American Blacksmith. 

"The best way for any rider to thoroughly understand his machine, is to get a copy of this 

book; it is worth many times its price." — Pacific Motorcyclist. 

AUTOMOBILE AND MOTORCYCLE CHARTS 

Chart. Location of Gasoline Engine Troubles Made Easy — A Chart Show- 
ing Sectional View of Gasoline Engine. Compiled by Victor W. Page, 
M.S.A.E. 

It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type. 

It outlines distinctly all parts liable to give trouble and also details the derangements apt 

to interfere with smooth engine operation. 

Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen,. 

chauffeurs, motorboat owners, motor-truck and tractor drivers, aviators, motor-cyclists, 

and all others who have to do with gasoline power plants. 

It simplifies location of all engine troubles, and while it will prove invaluable to the novice, 

it can be used to advantage by the more expert. It should be on the walls of every publio 

and private garage, automobile repair shop, club house or school. It can be carried in the 

automobile or pocket with ease, and will insure againct loss of time when engine trouble 

manifests itself. 

This sectional view of engine is a complete review of all motor troubles. It is prepared by a 

practical motorist for all who motor. More information for the money than ever before 

offered. No details omitted. Size 25x38 inches. Securely mailed on receipt of JJ5 CentS- 



Chart. Location of Ford Engine Troubles Made Easy. 

W. Page, M.S.A.E. 



Compiled by Victor. 



This shows clear sectional views depicting all portions of the Ford power plant and auxiliary 
groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and 
cooling system, that are apt to give trouble, detailing all derangements that are liable to- 
make an engine lose power, start hard or work irregularly. This chart is valuable to students, 
owners, and drivers, as it simplifies location of all engine faults. Of great advantage as an 
instructor for the novice, it can be used equally well by the more expert as a work of reference 
and review. It can be carried in the tool-box or pocket with ease and will save its cost in 
labor eliminated the first time engine trouble manifests itself. Prepared with special refer- 
ence to the average man's needs and is a practical review of all motor troubles because it is based, 
on the actual experience of an automobile engineer-mechanic with the mechanism the chart 
describes. It enables the non-technical owner or operator of a Ford car to locate engine 
derangements by systematic search, guided by easily recognized symptoms instead of by 
guesswork. It makes the average owner independent of the roadside repair shop when tour- 
ing. Must be seen to be appreciated. Size 25x38 inches. Printed on heavy bond paper. 

Price 25 cents 



Chart. Lubrication of the Motor Car Chassis. 

Page, M.S.A.E. 



Compiled by Victor W. 



This chart presents the plan view of a typical six-cylinder chassis of standard design and alt 
parts are clearly indicated that demand oil, also the frequency with which they must be 
lubricated and the kind of oil to use. A practical chart for all interested in motor-car main- 
tenance. Size 24x38 inches. Price JJ5 CentS- 



Compiled by Victor. 



Chart. Location of Carbureton Troubles Made Easy. 

W. Page, M.S.A.E. 

This chart shows all parts of a typical pressure feed fuel supply system and gives causes of 
trouble, how to locate defects and means of remedying them. Size 24x38 inches. 

Price . 25 cents 

Chart. Location of Ignition System Troubles Made Easy. Compiled by 
Victor W. Page, M.S.A.E. 

In this diagram all parts of a typical double ignition system using battery and magneto current- 
are shown, and suggestions are given for readily finding ignition troubles and eliminating: 
them when found. Size 24x38 inches. Price 25 Cents. 



L 



CATALOGUE OF GOOD, PRACTICAL BOOKS 7 

Chart. Location of Cooling and Lubrication System Faults. Compiled by 
Victor W. Page, M.S.A.E. 

This composite diagram shows a typical automobile power plant using pump circulated 
water-cooling system and the most popular lubrication method. Gives suggestions for cur- 
ing all overheating and loss of power faults due to faulty action of the oiling or cooling group. 
Size 24x38 inches. Price 25 Cents 

Chart. Motorcycle Troubles Made Easy. Compiled by Victor W. Page, 
M.S.A.E. 

A chart showing sectional view of a single-cylinder gasoline engine. This chart simplifies 
location of all power-plant troubles. A single-cylinder motor is shown for simplicity. It 
outlines distinctly all parts liable to give trouble and also details the derangements apt to 
interfere with smooth engine operation. This chart will prove of value to all who have to do 
with the operation, repair or sale of motorcycles. No details omitted. Size 30x20 inches. 

I^ce 25 cents 

AVIATION 

Aviation Engines, their Design, Construction, Operation and Repair. By 

Lieut. Victor W. Page, Aviation Section, S.C.U.S.R. 

A practical work containing valuable instructions for aviation students, mechanicians, 
squadron engineering officers and all interested in the construction and upkeep of airplane 
power plants. 

The rapidly increasing interest in the study of aviation, and especially of the highly developed 
internal combustion engines that make mechanical flight possible, has created a demand for a 
text-book suitable for schools and home study that will clearly and concisely explain the 
workings of the various aircraft engines of foreign and domestic manufacture. 
This treatise, written by a recognized authority on all of the practical aspects of internal 
combustion engine construction, maintenance and repair fills the need as no other book does. 
The matter is logically arranged; all descriptive matter is simply expressed and copiously 
illustrated so that anyone can understand airplane engine operation and repair even if with- 
out previous mechanical training. This work is invaluable for anyone desiring to become an 
aviator or aviation mechanician. 

The latest rotary types, such as the Gnome, Monosoupape, and Le Rhone, are fully explained, 
as well as the recently developed Vee and radial types. The subjects of carburetion, ignition, 
cooling and lubrication also are covered in a thorough manner. The chapters on repair and 
maintenance are distinctive and found in no other book on this subject. 
Invaluable to the student, mechanic and soldier wishing to enter the aviation service. 
Not a technical book, but a practical, easily understood work of reference for all interested 
in aeronautical science. 576 octavo pages. 253 specially made engravings. Price . §3.00 net 

GLOSSARY OF AVIATION TERMS 



Termes D' Aviation, English-French, French-English. Compiled by Lieuts. 
Victor W. Page, A.S., S.C.U.S.R., and Paul Montariol of the French 
Flying Corps, on duty on Signal Corps Aviation School, Mineola, L. I. 

A complete, well illustrated volume intended to facilitate conversation between English- 
speaking and French aviators. A very valuable book for all who are about to leave for duty 
overseas. 

Approved for publication by Major W. G. Kilner, S.C., U.S.C.O. Signal Corps Aviation 
School. Hazlehurst Field, Mineola, L.I. 

This book should be in every Aviator's and Mechanic's Kit for ready reference. 128 pages. 
Fully illustrated with detailed engravings. Price $1.00 

Aviation Chart. Location of Airplane Power Plant Troubles Made Easy. 

By Lieut. Victor W. Page, A.S., S.C.U.S.R. 

A large chart outlining all parts of a typical airplane power plant, showing the points where 
trouble is apt to occur and suggesting remedies for the common defects. Intended espe- 
cially for Aviators and Aviation Mechanics on School and Field Duty. Price . . 50 Cents 

BRAZING AND SOLDERING 

Brazing and Soldering. By James F. Hobart. 

The only book that shows you just how to handle any job of brazing or soldering that comes 
along; it tells > ou what mixture to use, how to make a furnace if you need one. Full of valu- 
able kinks. The fifth edition of this book has just been published, and to it much now mat- 
ter and a large number of tested formula? for all kinds of solders and fluxes have been added. 
Illustrated. Price 25 Cents 



8 THE NORMAN W. HENLEY PUBLISHING CO. 

CHART S 

Aviation Chart. Location of Airplane Power Plant Troubles Made Easy. 

By Lieut. Victor W. Page, A.S., S.C.U.S.R. 

A large chart outlining all parts of a typical airplane power plant, showing the points where 
trouble is apt to occur and suggesting remedies for the common defects. Intended especially 
for Aviators and Aviation Mechanics on School and Field Duty. Price .... 5Q cents 

Gasoline Engine Troubles Made Easy — A Chart Showing Sectional View of 
Gasoline Engine. Compiled by Lieut. Victor W. Page, A.S., S.C.U.S.R. 

It shows clearly all parts of a typical four-cylinder gasoline engine of the four-cycle type. 
It outlines distinctly all parts liable to give trouble and also details the derangements apt 
to interfere with smooth engine operation. 

Valuable to students, motorists, mechanics, repairmen, garagemen, automobile salesmen, 
chauffeurs, motor-boat owners, motor-truck and tractor drivers, aviators, motor-cyclists, 
and all others who have to do with gasoline power plants. 

It simplifies location of all engine troubles, and while it will prove invaluable to the novice, 
it can be used to advantage by the more expert. It should be on the walls of every public 
and private garage, automobile repair shop, club house or school. It can be carried in the 
automobile or pocket with ease and will insure against loss of time when engine trouble mani- 
fests itself. 

This sectional view of engine is a complete review of all motor troubles. It is prepared by a 
practical motorist for all who motor. No details omitted. Size 25x38 inches. Price £5 Cents 

Lubrication of the Motor Car Chassis. 

This chart presents the plan view of a typical six-cylinder chassis of standard design and 
all parts are clearly indicated that demand oil, also the frequency with which they must be 
lubricated and the kind of oil to use. A practical chart for all interested in motor-car main- 
tenance. Size 24x38 inches. Price 25 Cents 

Location of Carburetion Troubles Made Easy. 

This chart shows all parts of a typical pressure feed fuel supply system and gives causes of 
trouble, how to locate defects and means of remedying them. Size 24x38 inches. 

P«ce 25 cents 

Location of Ignition System Troubles Made Easy. 

In this chart all parts of a typical double ignition system using battery and magneto current 
are shown and suggestions are given for readily finding ignition troubles and eliminating 
them when found. Size 24x38 inches. Price £5 Cents 

Location of Cooling and Lubrication System Faults. 

This composite chart shows a typical automobile power plant using pump circulated water- 
cooling system and the most popular lubrication method. Gives suggestions for curing all 
.overheating and loss of power faults due to faulty action of the oiling or cooling group. Size 
24x38 inches. Price 25 Cents 

Motorcycle Troubles Made Easy — A Chart Showing Sectional View of Single- 
Cylinder Gasoline Engine. Compiled by Victor W. Page, M.S.A.E. 

This chart simplifies location of all power-plant troubles, and will prove invaluable to all 
who have to do with the operation, repair or sale of motorcycles. No details omitted. Size 
25x38 inches. Price £5 cents 

Location of Ford Engine Troubles Made Easy. Compiled by Victor W. 
Page, M.S.A.E. 

This shows clear sectional views depicting all portions of the Ford power plant and auxiliary 
groups. It outlines clearly all parts of the engine, fuel supply system, ignition group and 
cooling system, that are apt to give trouble, detailing all derangements that are liable to 
make an engine lose power, start hard or work irregularly. This chart is valuable to students, 
owners, and drivers, as it simplifies location of all engine faults. Of great advantage as an 
instructor for the novice, it can be used equally well by the more expert as a work of reference 
and review. It can be carried in the toolbox or pocket with ease and will save its cost in 
labor eliminated the first time engine trouble manifests itself. Prepared with special refer- 
ence to the average man's needs and is a practical review of all motor troubles because it is 
based on the actual experience of an automobile engineer-mechanic with the mechanism the 
chart describes. It enables the non-technical owner or operator of a Ford car to locate en- 
gine derangements by systematic search, guided by easily recognized symptoms instead of 
by guesswork. It makes the average owner independent of the roadside repair shop when 
touring. Must be seen to be appreciated. Size 25x38 inches. Printed on heavy bond paper. 

Price 25 cents 



CATALOGUE OF GOOD, PRACTICAL BOOKS 9 

Modern Submarine Chart — with Two Hundred Parts Numbered and Named. 

A cross-section view, showing clearly and distinctly all the interior of a Submarine of the 
latest type. You get more information from this chart, about the construction and opera- 
tion of a Submarine, than in any other way. No details omitted — everything is accurate 
and to scale. It is absolutely correct in every detail, having been approved by Naval En- 
gineers. ' All the machinery and devices fitted in a modern Submarine Boat are shown, and 
to make the engraving more readily understood all the features are shown in operative form, 
with Officers and Men in the act of performing the duties assigned to them in service con- 
ditions. This CHART IS REALLY AN ENCYCLOPEDIA OF A SUBMARINE. It 
is educational and worth many times its cost. Mailed in a Tube for 25 Cents 

Box Car Chart. 

A chart showing the anatomy of a box car, having every part of the car numbered and its 
proper name given in a reference list. Price 25 Cents 

Gondola Car Chart. 

A chart showing the anatomy of a gondola car, having every part of the car numbered and 
its proper reference name given in a reference list. Price 25 Cents 

Passenger- Car Chart. 

A chart showing the anatomy of a passenger-car, having every part of the car numbered 
and its proper name given in a reference list 25 cents 

Steel Hopper Bottom Coal Car. 

A chart showing the anatomy of a steel Hopper Bottom Coal Car, having every part of the 
car numbered and its proper name given in a reference list. Price . „ 25 Cents 

Tractive Power Chart. 

A chart whereby you can find the tractive power or drawbar pull of any locomotive without 
making a figure. Shows what cylinders are equal, how driving wheels and steam pressure 
affect the power. What sized engine you need to exert a given drawbar pull or anything you 
desire in this line. Price 50 cents 

Horse-Power Chart. 

Shows the horse-power of any stationary engine without calculation. No matter what the 
cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether con- 
densing or non-condensing, it's all there. Easy to use, accurate, and saves time and calcu- 
lations. Especially useful to engineers and designers. Price 50 cents 

Boiler Room Chart. By Geo. L. Fowler. 

A chart — size 14x28 inches — showing in isometric perspective the mechanisms belonging in 
a modern boiler room. The various parts are shown broken or removed, so that the internal 
construction is fully illustrated. Each part is given a reference number, and these, with the 
corresponding name, are given in a glossary printed at the sides. This chart is really a dic- 
tionary of the boiler room — the names of more than 200 parts being given. Price . 25 Cents 



COKE 

Modern Coking Practice, Including Analysis of Materials and Products. 

By J. E. Christopher and T. H. Byrom. 

This, the standard work on the subject, has just bppn revised. It is a practical work for those 
engaged in Coke manufacture and the recovery of By-products. Fully illustrated with fold- 
ing olates. It has been the aim of the authors, in preparing this book, to produce one which 
shall be of use and benefit to those who are associated with, or interested in, the modern 
develonments of the industry. Among the Chapters contained in Volume I are: Introduc- 
tion; Classification of Fuels; Imnurities of Coals; Coal Washing; Sampling and Valuation 
of Coals, etc.; Power of Fuels; History of Coke Manufacture; Developments in the Coke 
Oven Design; Recent Types of Coke Ovens; Mechanical Appliances at Coke Ovens; Chem- 
ical and Physical Examination of Coke. Volume II covers fully the subject of Bv-Products. 
^rice, per volume $3.00 net 



10 THE NORMAN W. HENLEY PUBLISHING CO. 

COMPRESSED AIR 

Compressed Air in AH Its Applications. By Gardner D. Hiscox. 

This is the most complete book on the subject of Air that has ever been issued, and its thirty- 
five chapters include about every phase of the subject one can think of. It may be called 
an encyclopedia of compressed air. It is written by an expert, who, in its 665 pages, has 
dealt with the subject in a comprehensive manner, no phase of it being omitted. Includes 
the physical properties of air from a vacuum to its highest pressure, its thermodynamics, 
compression, transmission and uses as a motive power, in the Operation of Stationary and 
Portable Machinery, in Mining, Air Tools, Air Lifts, Pumping of Water, Acids, and Oils; 
the. Air Blast for Cleaning and Painting the Sand Blast and its Work, and the Numerous 
Appliances in which Compressed Air is a .Most Convenient and Economical Transmitter of 
.Power for Mechanical Work, Railway Propulsion, Refrigeration, and the Various Uses to which 
Compressed Air has been applied. Includes forty-four tables of the physical properties of 
air, its compression, expansion, and volumes required for various kinds of work, and a list 
of patents on compressed air from 1875 to date. Over 500 illustrations, 5th Edition, re- 
vised and enlarged. 

Cloth bound. Price $5.00 

Half Morocco. Price $6.50 

CONCRETE 

Concrete Workers' Reference Books. A Series of Popular Handbooks for 
Concrete Users. Prepared by A. A. Houghton .50 cents 

The author, in preparing this Series, has not only treated on the usual types of construction, but 
explains and illustrates molds and systems thai are not patented, but which are equal in value 
and often superior to those restricted by patents. These molds are very easily and cheaply con- 
structed and embody simplicity, rapidity of operation, and the most successful results in the molded 
concrete. Each of these books is fully illustrated, and the subjects are exhaustively treated in plain 
English. 

Concrete Wall Forms. By A. A. Houghton. 

A new automatic wall clamp is illustrated with working drawings. Other types of wall forms, 
clamps, separators, etc., are also illustrated and explained. (No. 1 of Series) Price 50 Cents 

Concrete Floors and Sidewalks. By A. A. Houghton. 

The molds for molding squares, hexagonal and many other styles of mosaic floor and side- 
walk blocks are fully illustrated and explained. (No. 2 of Series) Price 50 Cents 

Practical Concrete Silo Construction. By A. A. Houghton. 

Complete working drawings and specifications are given for several styles of concrete silos, 
with illustrations of molds for monolithic and block silos. The tables, data, and information 
presented in this book are of the utmost value in planning and constructing all forms of con- 
crete silos. (No. 3 of Series) Price 50 Cents 

Molding Concrete Chimneys, Slate and Roof Tiles. By A. A. Houghton. 

The manufacture of all types of concrete slate and roof tile is fully treated. Valuable data 
on all forms of reinforced concrete roofs are contained within its pages. The construction 
of concrete chimneys by block and monolithic systems is fully illustrated and described. A 
number of ornamental designs of chimney construction with molds are shown in this valuable 
treatise. (No. 4 of Series.) Price 50 Cents 

Molding and Curing Ornamental Concrete. By A. A. Houghton. 

The proper proportions of cement and aggregates for various finishes, also the method of 
thoroughly mixing and placing in the molds, are fully treated. An exhaustive treatise on 
this subject that every concrete worker will find of daily use and value. (No. 5 of Series.) 

Prioe 50 cents 

Concrete Monuments, Mausoleums and Burial Vaults. By A. A. Houghton. 

The molding of concrete monuments to imitate the most expensive cut stone is explained 
in this treatise, with working drawings of easily built molds. Cutting inscriptions and de- 
signs are also fully treated. (No. 6 of Series.) Price 50 Cents 

Molding Concrete Bathtubs, Aquariums and Natatoriums. By A. A. 

Houghton. 

Simple molds and instruction are given for molding many styles of concrete bathtubs, swim- 
ming-pools, etc. These molds are easily built and permit rapid and successful work. (No. 7 
of Series.) Price 50 Cents 



CATALOGUE OF GOOD, PRACTICAL BOOKS 11 



Concrete Bridges, Culverts and Sewers. By A. A. Houghton. 

A number of ornamental concrete bridges with illustrations of molds are given. A collapsible 
center or core for bridges, culverts and sewers is fully illustrated with detailed instructions 
for building. (No. 8 of Series.) Price 50 Cents 

Constructing Concrete Porches. By A. A. Houghton. 

A number of designs with working drawings of molds are fully explained so any one can easily 
construct different styles of ornamental concrete porches without the purchase of expensive 
molds. (No. 9 of Series.) Price 50 cents 

Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc. By A. A. Houghton. 

The molds for producing many original designs of flower-pots, urns, flower-boxes, jardinieres, 
etc., are fully illustrated and explained, so the worker can easily construct and operate same. 
(No. 10 of Series.) Price 50 Cents 

Molding Concrete Fountains and Lawn Ornaments. By A. A. Houghton. 

The molding of a number of designs of lawn seats, curbing, hitching posts, pergolas, sun dials 
and other forms of ornamental concrete for the ornamentation of lawns and gardens, is fully 
illustrated and described. (No. 11 of Series.) Price 50 Cents 

Concrete from Sand Molds. By A. A. Houghton. 

A Practical Work treating on a process which has heretofore been held as a trade secret by 
the few who possessed it, and which wall successfully mold every and any class of ornamental 
concrete work. The process of molding concrete with sand molds is of the utmost practical 
value, possessing the manifold advantages of a low cost of molds, the ease and rapidity of 
operation, perfect details to all ornamental designs, density and increased strength of the 
concrete, perfect curing of the work without attention and the easy removal of the molds 
regardless of any undercutting the design may have. 192 pages. Fully illustrated 
Price 1^.00 

Ornamental Concrete without Molds. By A. A. Houghton. 

The process for making ornamental concrete without molds has long been held as a secret, 
and now, for the first time, this process is given to the public. The book reveals the secret 
and is the only book published which explains a simple, practical method whereby the con- 
crete worker is enabled, by employing wood and metal templates of different designs, to mold 
or model in concrete any Cornice, Archivolt, Column, Pedestal, Base Cap, Urn or Pier in a 
monolithic form — right upon the job. These may be molded in units or blocks and then built 
up to suit the specifications demanded. This work is fully illustrated, with detailed engrav- 
ings. Price $2.00 

Concrete for the Farm and in the Shop. By H. Colin Campbell, C.E., E.M. 

"Concrete for the Farm and in the Shop" is a new book from cover to cover, illustrating and 
describing in plain, simple language many of the numerous applications of concrete within 
the range of the home worker. Among the subjects treated are: Principles of Reinforcing; 
Methods of Protecting Concrete so as to Insure Proper Hardening; Home-made Mixers; 
Mixing by Hand and Machine; Form Construction, Described and Illustrated by Draw- 
ings and Photographs; Construction of Concrete Walls and Fences; Concrete Fence Posts; 
Concrete Gate Posts; Corner Posts; Clothes Line Posts; Grape Arbor Posts; Tanks; 
Troughs; Cisterns; Hog Wallows; Feeding Floors and Barnyard Pavements; Foundations; 
Well Curbs and Platforms; Indoor Floors; Sidewalks; Steps; Concrete Hotbeds and Cold 
Frames; Concrete Slab Roofs; Walls for Buildings; Repairing Leaks in Tanks and Cisterns; 
and all topics associated with these subjects as bearing upon securing the best results from 
concrete are dwelt upon at sufficient length in plain every-day English so that the inexperi- 
enced person desiring to undertake a piece of concrete construction can, by following the 
directions set forth in this book, secure 100 per cent, success every time. A number of con- 
venient and practical tables for estimating quantities, and some practical examples, are also 
given.* (5x7.) 149 pages. 51 illustrations. Price 75 cents 

Popular Handbook for Cement and Concrete Users. By Myron H. Lewis. 

This is a concise treatise of the principles and methods employed in the manufacture and use 
of cement in all classes of modern works. The author has brought together in this work all 
the salient matter of interest to the user of concrete and its many diversified products. The 
matter is presented in logical and systematic order, clearly written, fully illustrated and free 
from involved mathematics. Everything of value to the concrete user is given, including 
kinds of cement employed in construction, concrete architecture, inspection and testing, 
waterproofing, coloring and painting, rules, tables, working and cost data. The book com- 
prises thirty-three chapters, as follow: Introductory. Kinds of Cement and How They 
are Made. Properties. Testing and Requirements of Hydraulic Cement. Concrete and Its 
Properties. Sand, Broken Stone and Gravel for Concrete. How to Proportion the Materials. 
How to Mix and Place Concrete. Forms of Concrete Construction. The Architectural and 
Artistic Possibilities of Concrete. Concrete Residences. Mortars, Plasters and Stucco, 
and How to Use Them. The Artistic Treatment of Concrete Surfaces. Concrete Building 



12 THE NORMAN W. HENLEY PUBLISHING CO. 

Blocks. The Making of Ornamental Concrete. Concrete Pipes, Fences, Posts, etc* Essen- 
tial Features and Advantages of Reenforced Concrete. How to Design Reenforced Con- 
crete Beams, Slabs and Columns. Explanations of the Methods and Principles in Designing 
Reenforced Concrete, Beams and Slabs. Systems of Reenforcement Employed. Reen- 
forced Concrete in Factory and General Building Construction. Concrete in Foundation Work. 
Concrete Retaining Walls, Abutments and Bulkheads. Concrete Arches and Arch Bridges. 
Concrete Beam and Girder Bridges. Concrete in Sewerage and Draining Works. Concrete 
Tanks, Dams and Reservoirs. Concrete Sidewalks, Curbs and Pavements. Concrete in 
Railroad Construction. The Utility of Concrete on the Farm. The Waterproofing of Con- 
crete Structures. Grout of Liquid Concrete and Its Use. Inspection of Concrete Work. 
Cost of Concrete Work. Some of the special features of the book are: 1. — The Attention 
Paid to the Artistic and Architectural Side of Concrete Work. 2. — The Authoritative Treat- 
ment of the Problem of Waterproofing Concrete. 3. — An Excellent Summary of the Rules 
to be Followed in Concrete Construction. 4. — The Valuable Cost Data and Useful Tables 
given. A valuable Addition to the Library of Every Cement and Concrete User. Price . $2.50 

WHAT IS SAID OF THIS BOOK: 

"The field of Concrete Construction is well covered and the matter contained is well within 
the understanding of any person." — Engineering-Contracting. 

"Should be on the bookshelves of every contractor, engineer, and architect in the land." — 
National Builder. 

Waterproofing Concrete. By Myron H. Lewis. 

Modern Methods of Waterproofing Concrete and Other Structures. A condensed statement 
of the Principles, Rules, and Precautions to be Observed in Waterproofing and Dampproofing 
Structures and Structural Materials. Paper binding. Illustrated. Price .... 50 Cents 

DICTIONARIES 

Aviation Terms, Termes D'Aviation, English-French, French-English. 

Compiled by Lieuts. Victor W. Page, A.S., S.C.U.S.R., and Paul Mon- 
tariol, of the French Flying Corps, on duty on Signal Corps Aviation School, 
Mineola, L. I. 

The lists contained are confined to essentials, and special folding plates are included to show 
all important airplane parts. The lists are divided in four sections as follows: 1. — Flying 
Field Terms. 2.— The Airplane. 3.— The Engine. 4.— Tools and Shop Terms. 
A complete, well illustrated volume intended to facilitate conversation between English-speak- 
ing and French aviators. A very valuable book for all who are about to leave for duty over- 
seas. 

Approved for publication by Major W. G. Kilner, S.C., U.S. CO. Signal Corps Aviation School, 
Hazelhurst Field, Mineola, L. I. This book should be in every Aviator's and Mechanic's Kit 
for ready reference. 128 pages, fully illustrated, with detailed engravings. Price . . $1,00 

Standard Electrical Dictionary. By T. O'Conor Sloane. 

An indispensable w-.rk to all interested in electrical science. Suitable alike for the student 
and professional. A practical handbook of reference containing definitions of about 5,000 
distinct words, terms and phrases. The definitions are terse and concise and include every 
term used in electrical science. Recently issued. An entirely new edition. Should be in 
the possession of all who desire to keep abreast with the progress of this branch of science. 
Complete, concise and convenient. 682 pages, 393 illustrations. Price $3.00 

DIES— METAL WORK 

Dies: Their Construction and Use for the Modern Working of Sheet Metals. 

By J. V. Woodworth. 

A most useful book, and one which should be in the hands of all engaged in the press working 
of metals; treating on the Designing, Constructing, and Use of Tools, Fixtures and Devices, 
together with the manner in which they should be used in the Power Press, for the cheap and 
rapid production of the great variety of sheet-metal articles now in use. It is designed 
as a guide to the production of sheet-metal parts at the minimum of cost with the 
maximum of output. The hardening and tempering of Press tools and the classes of work 
which may be produced to the best advantage by the use of dies in the power press are fully 
treated. Its 515 illustrations show dies, press fixtures and sheet-metal working devices, the 
descriptions of which are so clear and practical that all metal-working mechanics will be able 
to understand how to design, construct and use them. Many of the dies and press fixtures 
treated were either constructed by the author or under his supervision. Others were built by 
skilful mechanics and are in use in large sheet-metal establishments and machine shops. 
6th Revised and Enlarged Edition. Price '. $3.00 



CATALOGUE OF GOOD, PRACTICAL BOOKS 13 

Punches, Dies and Tools for Manufacturing in Presses. By J. V. Wood- 
worth. 

This work is a companion volume to the author's elementary work entitled "Dies: Their 
Construction and Use." It does not go into the details of die-making to the extent of the 
author's previous book, but gives a comprehensive review of the field of operations carried on 
by presses. A large part of the information given has been drawn from the author's personal 
experience. It might well be termed an Encyclopedia of Die-Making, Punch-Making, Die- 
Sinking, Sheet-Metal Working, and Making of Soecial Tools, Sub-presses, Devices and Mechani- 
cal Combinations for Punching, Cutting, Bending, Forming, Piercing, Drawing, Compressing 
and Assembling Sheet-Metal Parts, and also Articles of other Materials in Machine Tools. 
2d Edition. Price $4.00 

Drop Forging, Die-Sinking and Machine-Forming of Steel. By J. V, 

WoODWORTH. 

This is a practical treatise on Alodern Shop Practice, Processes, Methods, Machine Tools,. 
and Details treating on the Hot and Cold Machine-Forming of Steel and Iron into Finished- 
Shapes: together with Tools, Dies, and Machinery involved in the manufacture of Duplicate 
Forgings and Interchangeable Hot and Cold Pressed Parts from Bar and Sheet Metal. This- 
book fills a demand of long standing for information regarding drop-forgings, die-sinking and 
machine-forming of steel and the shop practice involved, as it actually exists in the modern 
drop-forging shop. The processes of die-sinking and force-making, which are thoroughly 
described and illustrated in this admirable work, are rarely to be found explained in such a 
clear and concise manner as is here set forth. The process of die-sinking relates to the engrav- 
ing or sinking of the female or lower dies, such as are used for drop-forgings, hot and cold 
machine-forging, swedging, and the press working of metals. The process of force-making 
relates to the engraving or raising of the male or upper dies used in producing the lower dies 
for the press-forming and machine-forging of duplicate parts of metal. 

In addition to the arts above mentioned the book contains explicit information regarding the 
drop-forging and hardening plants, designs, conditions, equipment, drop hammers, forging 
machines, etc., machine forging, hydraulic forging, autogenous welding and shop practice. 
The book contains eleven chapters, and the information contained in these chapters is just 
what will prove most valuable to the forged-metal worker. All operations described in the 
work are thoroughly illustrated by means of perspective half-tones and outline sketches of 
the machinery employed. 300 detailed illustrations. Price §2.50 

DRAWING— SKETCHING PAPER 



Practical Perspective. By Richards and Colvin. 

Shows just how to make all kinds of mechanical drawings in the only practical perspective 
isometric Makes everything plain, so that any mechanic can understand a sketch or drawing 
in this way. Saves time in the drawing room, and mistakes in the shops. Contains practical 
examples el various classes of work. 4th Edition. Price 50 CClltS 

Linear Perspective Self-Taught. By Herman T. C. Kratjs. 

This work gives the theory and practice of linear perspective, as used in architectural, engineer- 
ing and mechanical drawings. Persons taking up the study of the subject by themselves will 
be able, by the use of the instruction given, to readily grasp the subject, and by reasonable 
practice become good perspective draftsmen. The arrangement of the book is good; the plate 
is on the left-hand, while the descriptive text follows on the opposite page, so as to be readily 
referred to. The drawings are on sufficiently large scale to show the work clearly and are 
plainly figured. There is included a self-explanatory chart which gives all information neces- 
sary for the thorough understanding of perspective. This chart alone is worth many times 
over the price of the book. 2d Revised and Enlarged Edition. Price §2.50 

Self-Taught Mechanical Drawing and Elementary Machine Design. By 

F. L. Sylvester, M.E., Draftsman, with additions by Erik Oberg, associate 
editor of "Machinery." 

This is a practical treatise on Mechanical Drawing and Machine Design, comprising the first 
principles of geometric and mechanical drawing, workshop mathematics, mechanics, strength 
of materials and the calculations and design of machine details. The author's aim has been 
to adapt this treatise to the requirements of the practical mechanic and young draftsman 
and to present the matter in as clear and concise a manner as possible. To meet the demands 
of this class of students, practically all the important elements of machine design have boon 
dealt with, and in addition algebraic formulas have been explained, and the elements of 
trigonometry treated in the manner best suited to the needs of the practical man. The book 
is divided into 20 chapters, and in arranging the material, mechanical drawing, pure and simple, 
has been taken up first, as a thorough understanding of the principles of representing objects 
facilitates the further study of mechanical subjects. This is followed by the mathematics 
necessary for the solution of the problems in machine design which are presented later, and a 
practical introduction to theoretical mechanics and the Btrength of materials. The various 
elements entering into machine design, such as cams, gears, sprocket-wheels, cone pulleys, 
bolts, screws, couplings, clutches, shafting and fly-wheels, have been treated in such a way 
as to make possible the use of the work as a text-book for a continuous course of study. It 
is easily comprehended and assimilated even by students of limited previous training. 330 
pages, 215 engravings. Price $2.00 



14 THE NORMAN W. HENLEY PUBLISHING CO. 



A New Sketching Paper. 

A new specially ruled paper to enable you to make sketches or drawings in isometric perspec- 
tive without any figuring or fussing. It is being used for shop details as well as for assembly 
drawings, as it makes one sketch do the work of three, and no workman can help seeing lust 
what is wanted. & J 

Pads of 40 sheets, 6x9 inches. Price „ a? ppnfc 

Pads of 40 sheets, 9x12 inches. Price fjft ppiitc 

40 sheets, 12x18 inches. Price ...... '. $1 Oft 

ELECTRICITY 



Arithmetic of Electricity. By Prof. T. O'Conor Sloane. 

A practical treatise on electrical calculations of all kinds reduced to a series of rules, all of the 
simplest forms, and involving only ordinary arithmetic; each rule illustrated by one or more 
practical problems, with detailed solution of each one. This book is classed among the most 
useful works published on the science of electricity, covering as it does the mathematics of 
electricity in a manner that will attract the attention of those who are not familiar with alge- 
braical formulas. 20th Edition. 160 pages. Price $1.00 

Commutator Construction. By Wm. Baxter, Jr. 

The business end of any dynamo or motor of the direct current type is the commutator. This 
book goes into the designing, building, and maintenance of commutators, shows how to locate 
troubles and how to remedy them; everyone who fusses with dynamos needs this. 4th Edition. 

Price 25 cents 

Dynamo Building for Amateurs, or How to Construct a Fifty- Watt Dynamo. 

By Arthur J. Weed, Member of N. Y. Electrical Society. 

A practical treatise showing in detail the construction of a small dynamo or motor, the entire 
machine work of which can be done on a small foot lathe. Dimensioned working drawings 
are given for each piece of machine work, and each operation is clearly described. This 
machine, when used as a dynamo, has an output of fifty watts; when used as a motor it will 
drive a small drill press or lathe. It can be used to drive a sewing machine on any and all 
ordinary work. The book is illustrated with more than sixty original engravings, showing the 
actual construction of the different parts. Among the contents are chapters on: 1. Fifty-Watt 
Dynamo. 2. Side Bearing Rods. 3. Field Punching. 4. Bearings. 5. Commutator. 6. 
Pulley. 7. Brush Holders. 8. Connection Board. 9. Armature Shaft. 10. Armature. 
11. Armature Winding. 12. Field Winding. 13. Connecting and starting. 

Paper. Price 50 cents 

Cloth. Price $1.0ft 

Electric Bells. By M. B. Sleeper. 

A complete treatise for the practical worker in Installing, Operating and Testing Bell Circuits, 
Burglar Alarms, Thermostats, and other apparatus used with Electric Bells. 
Both the electrician and the experimenter will find in this book new material which is essential 
in their work. Tools, bells, batteries, unusual circuits, burglar alarms, annunciator systems, 
thermostats, circuit breakers, time alarms, and other apparatus used in bell circuits are de- 
scribed from the standpoints of their application, construction and repair. The detailed 
instruction for building the apparatus will appeal to the experimenter particularly. 
The practical worker will find the chapter on Wiring, Calculation of Wire Sizes and Magnet 
Winding, Upkeep of Systems, and the Location of Faults, of the greatest value in their work. 
Among the chapters are: Tools and Materials for Bell Work; How and Why Bell Work; 
Batteries for Small Installations; Making Bells and Push Buttons; Wiring Bell Systems; 
Construction of Annunciators and Signals; Burglary Alarms and Auxiliary Apparatus; More 
Elaborate Bell Systems; Finding Faults and Remedying Them. 124 pages, fully illustrated. 

Price 50 cents 

Electric Lighting and Heating Pocket Book. By Sydney F. Walker. 

This book puts in convenient form useful information regarding the apparatus which is likely 
to be attached to the mains of an electrical company. Tables of units and equivalents are in- 
cluded and useful electrical laws and formulas are stated. 438 pages, 300 engravings. Bound 
in leather. Pocket book form. Price $3.00 

Electric Wiring, Diagrams and Switchboards. By Newton Harrison, with 
additions by Thomas Poppe. 

A thoroughly practical treatise covering the subject of Electric Wiring in all its branches, 
including explanations and diagrams which are thoroughly explicit and greatly simplify the 
subject. Practical, every-day problems in wiring are presented and the method of obtain- 
ing intelligent results clearly shown. Only arithmetic is used. Ohm's law is given a sim- 
ple explanation with reference to wiring for direct and alternating currents. The funda- 
mental principle of drop of potential in circuits is shown with its various applications. The 
simple circuit is developed with the position of mains, feeders and branches; their treatment 



CATALOGUE OF GOOD, PRACTICAL BOOKS 15 

as a part of a wiring plan and their employment in house wiring clearly illustrated. Some 
simple facts about testing are included in connection with the wiring. Molding and conduit 
work are given careful consideration; and switchboards are systematically treated, built up 
and illustrated, showing the purpose they serve, for connection with the circuits, and to shunt 
and compound wound machines. The simple principles of switchboard construction, the 
development of the switchboard, the connections of the various instruments, including the 
lightning arrester, are also plainly set forth. 

Alternating current wiring is treated, with explanations of the power factor, conditions calling 
for various sizes of wire, and a simple way of obtaining the sizes for single-phase, two-phase 
and three-phase circuits. This is the only complete work issued showing and telling you what 
you should know about direct and alternating current wiring. It is a ready reference. The 
work is free from advanced technicalities and mathematics, arithmetic being used throughout. 
It is in every respect a handy, well-written, instructive, comprehensive volume on wiring 
for the wireman, foreman, contractor, or electrician. 2nd Revised Edition. 303 pages, 130 
illustrations. Price $1.50 

Electric Furnaces and their Industrial Applications. By J. Wright. 

This is a book which wall prove of interest to many classes of people; the manufacturer who 
desires to know what product can be manufactured successfully in the electric furnace, the 
chemist who wishes to post himself on the electro-chemistry, and the student of science who 
merely looks into the subject from curiosity. New, Revised and Enlarged Edition. 320 
Fully illustrated, cloth. Price $3.00 



Electric Toy Making, Dynamo Building, and Electric Motor Construction. 

By Prof. T. O' Conor Sloane. 

This work treats of the making at home of electrical toys, electrical apparatus, motors, dynamos, 
and instruments in general, and is designed to bring within the reach of young and old the 
manufacture of genuine and useful electrical appliances. The w T ork is especially designed for 
amateurs and young folks. 

Thousands of our young people are daily experimenting, and busily engaged in making elec- 
trical toys and apparatus of various kinds. The present work is just what is wanted to give 
the much needed information in a plain, practical manner, with illustrations to make easy 
the carrying out of the work. 20th Edition. Price 81.00 

Practical Electricity. By Prof. T. O'Conor Sloane. 

This work of 768 pages was previously known as Sloane's Electricians' Hand Book, and is 
intended for the practical electrican who has to make things go. The entire field of electricity 
is covered within its pages. Among some of the subjects treated are: The Theory of the 
Electric Current and Circuit, Electro-Chemistry, Primary Batteries, Storage Batteries, 
Generation and Utilization of Electric Powers, Alternating Current, Armature Winding, 
Dynamos and Motors, Motor Generators, Operation of the Central Station Switchboards, 
Safety Appliances, Distribution of Electric Light and Power, Street Mains, Transformers, 
Arc and Incandescent Lighting, Electric Measurements, Photometry, Electric Railways, 
Telephony, Bell-Wiring, Electric-Plating, Electric Heating, Wireless Telegraphy, etc. It 
contains no useless theory; everything is to the point. It teaches you just what you want 
to know about electricity. It is the standard work published on the subject. Forty-one 
chapters, 556 engravings. Price 82. 50 

Electricity Simplified. By Prof. T. O'Conor Sloane. 

The object of "Electricity Simplified" is to make the subject as plain as possible and 
to show what the modern conception of electricity is; to show how two plates of different 
metal, immersed in acid, can send a message around the globe; to explain how a bundle of 
copper wire rotated by a steam engine can be the agent in lighting our streets, to tell what the 
volt, ohm and ampere are, and what high and low tension mean; and to answer the questions 
that perpetually arise in the mind in this age of electricity. 13th Edition. 172 pages. Illus- 
trated. Price 81.00 

House Wiring. By Thomas W. Poppe. 

This work describes and illustrates the actual installation of Electric Light Wiring, the man- 
ner in which the work should be done, and the method of doing it. The book can be con- 
veniently carried in the pocket. It is intended for the Electrician, Helper and Apprentice. 
It solves all Wiring Problems and contains nothing that conflicts with the rulings of the 
National Board of Fire Underwriters. It gives just the information essential to the Success- 
ful Wiring of a Building. Among the subjects treated are: Locating the Meter. Panel- 
Boards. Switches. Plug Receptacles. Brackets. Ceiling Fixtures. The Meter Connec- 
tions. The Feed Wires. The Steel Armored Cable System. The Flexible Steel Conduit 
System. The Ridig Conduit System. A digest of the National Board of Fire Underwriters' 
rules relating to metallic wiring systems. Various switching arrangements explained and 
diagrammed. The easiest method of testing the Three- and Four-way circuits explained. 
The grounding of all metallic wiring systems and the reason for doing so shown and explained. 
The insulation of the metal parts of lamp fixtures and the reason for the same described and 
illustrated. 125 pages. 2nd Edition, revised and enlarged.- Fully illustrated. Flexible 

cloth. Price 50 cents 



16 THE NORMAN W. HENLEY PUBLISHING CO. 
How to Become a Successful Electrician. By Prof. T. 0' Conor Sloane. 

Every young man who wishes to become a successful electrician should read this book. It 
tells in simple language the surest and easiest way to become a successful electrician. The 
studies to be followed, methods of work, field of operation and the requirements of the suc- 
cessful electrician are pointed out and fully explained. Every young engineer will find this ah 
excellent steppmg stone to more advanced works on electricity which he must master before 
success can be attained. Many young men become discouraged at the very outstart by at- 
tempting to read and study books that are far beyond their comprehension. This book serves 
as the connecting link between the rudiments taught in the public schools and the real study 
of electricity. It is interesting from cover to cover. 18th Revised Edition, just issued. 205 
pages. Illustrated. Price $1.00 

Management of Dynamos. By Lummis-Paterson. 

A handbook of theory and practice. This work is arranged in three parts. The first part 
covers the elementary theory of the dynamo. The second part, the construction and action 
of the different classes of dynamos in common use are described; while the third part relates 
to such matters as affect the practical management and working of dynamos and motors. 
4th Edition. 292 pages, 117 illustrations. Price $1.50 

Standard Electrical dictionary. By T. O'Conor Sloane. 

An indispensable work to all interested in electrical science. Suitable alike for the student 
and professional. A practical handbook of reference containing definitions of about 5,000 
distinct words, terms and phrases. The definitions are terse and concise and include every 
term used in electrical science. Recently issued. An entirely new edition. Should be in the 
possession of all who desire to keep abreast with the progress of this branch of science. In 
its arrangement and typography the book is very convenient. The word or term defined is 
printed in black-faced type, which readily catches the eye, while the body of the page is in 
smaller but distinct type. The definitions are well worded, and so as to be understood by the 
non-technical reader. The general plan seems to be to give an exact, concise definition, and 
then amplify and explain in a more popular way. Synonyms are also given, and references 
to other words and phrases are made. A very complete and accurate index of fifty pages 
is at the end of the volume; and as this index contains all synonyms, and as all phrases art 
indexed in every reasonable combination of words, reference to the proper place in the body 
of the book is readily made. It is difficult to decide how far a book of this character is to 
keep the dictionary form, and to what extent it may assume the encyclopedia form. For 
some purposes, concise, exactly worded definitions are needed; for other purposes, more 
extended descriptions are required. This book seeks to satisfy both demands, and does it 
with considerable success. 682 pages, 393 illustrations. 12th Edition. 
Price $3.00 

Storage Batteries Simplified. By Victor W. Page, ME. 

A complete treatise on storage battery operating principles, repairs" and applications. 
The greatly increasing application of storage batteries in modern engineering and mechanical 
work has created a demand for a book that will consider this subject completely and exclu- 
sively. This is the most thorough and authoritative treatise ever published on this subject. 
It is written in easily understandable, non-technical language' so that any one may grasp 
the basic principles of storage battery action as well as their practical industrial applications. 
All electric and gasoline automobiles use storage batteries. Every automobile repairman, 
dealer or salesman should have a good knowledge of maintenance and repair of these impor- 
tant elements of the motor car mechanism. This book not only tells how to charge, care for 
and rebuild storage batteries but also outlines all the industrial uses. Learn how they run 
street cars, locomotives and factory trucks. Get an understanding of the important functions 
they perform in submarine boats, isolated lighting plants, railway switch and signal systems, 
marine applications, etc. This book tells how they are used in central station standby service, 
for starting automobile motors and in ignition systems. Every practical use of the modern 
storage battery is outlined in this treatise. 320 pages, fully illustrated. Price . . . $1.50 

Switchboards. By William Baxter, Jr. 

This book appeals to every engineer and electrician who wants to know the practical side 
of things. It takes up all sorts and conditions of dynamos, connections and circuits, and 
shows by diagram and illustration just how the switchboard should be connected. Includes 
direct and alternating current boards, also those for arc lighting, incandescent and power 
circuits. Special treatment on high voltage boards for power transmission. 2nd Edition. 
190 pages, Illustrated. Price . $1.50 

Telephone Construction, Installation, Wiring, Operation and Maintenance. 

By W. H. Radcliffe and H. C. Cushing. 

This book is intended for the amateur, the wireman, or the engineer who desires to establish 
a means of telephonic communication between the rooms of his home, office, or shop. It 
deals only with such things as may be of use to him rather than with theories. 
Gives the principles of construction and operation of both the Bell and Independent instru- 
ments; approved methods of installing and wiring them; the means of protecting them 
from lightning and abnormal currents; their connection together for operation as series or 
bridging stations; and rules for their inspection and maintenance. Line wiring and the wiring 
and operation of special telephone systems are also treated. Intricate mathematics are 
avoided, and all apparatus, circuits and systems are thoroughly described. The appendix 



CATALOGUE OF GOOD, PRACTICAL BOOKS 17 

contains definitions of units and terms used in the text. Selected wiring tables, which are very 
helpful, are also included. Among the subjects treated are Construction, Operation, and 
Installation of Telephone Instruments; Inspection and Maintenance 01 Telephone Instru- 
ments; Telephone Line Wiring; Testing Telephone Line Wires and Cables; Wiring and 
Operation of Special Telephone Systems, etc. 2nd Edition, Revised and Enlarged. 223 
154 illustrations $1.00 



Wireless Telegraphy and Telephony Simply Explained. By Alfred P. 
Morgan. 

This is undoubtedly one of the most complete and comprehensible treatises on the subject 
ever published, and a close study of its pages will enable one to master all the details of tht. 
wireless transmission of messages. The author has filled a long-felt want and has succeeded 
in furnishing a lucid, comprehensible explanation in, simple language of the theory and practice 
of wireless telegraphy and telephony. 

Among the contents are: Introductory; Wireless Transmission and Reception — The Aerial 
System, Earth Connections — The Transmitting Apparatus, Spark Coils and Transformers, 
Condensers, Helixes, Spark Gaps, Anchor Gaps, Aerial Switches — The Receiving Apparatus, 
Detectors, etc. — Tuning and Coupling, Tuning Coils, Loose Couplers, Variable Condensers, 
Directive Wave Systems — Miscellaneous Apparatus, Telephone Receivers, Range of Stations, 
Static Interference — Wireless Telephones, Sound and Sound Waves, The Vocal Cords and 
Ear — Wireless Telephone, How Sounds Are Changed into Electric Waves — Wireless Tele- 
phones, The Apparatus— Summary. 154 pages, 156 engravings. Price $1*00 

Wiring a House. By Herbert Pratt. 

Shows a house already built; tells just how to start about wiring it; where to begin; what 
wire to use; how to run it according to Insurance Rules; in fact, just the information you 
need. Directions apply equally to a shop. 4th Edition. Price J}5 Cents 

FACTORY MANAGEMENT, ETC. 

Modern Machine Shop Construction, Equipment and Management. By 

O. E. Perrigo, M.E. 

The only work published that describes the modern machine shop or manufacturing plant 
from the time the grass is growing on the site intended for it until the finished product is 
shipped. By a careful study of its thirty-two chapters the practical man may economically 
build, efficiently equip, and successfully manage the modern machine shop or manufacturing 
establishment. Just the book needed by those contemplating the erection of modern shop 
buildings, the rebuilding and reorganization of old ones, or the introduction of modern shop 
methods, time and cost systems. It is a book written and illustrated by a practical shop 
man for practical shop men who are too busy to read theories and want facts. It is the most 
complete all-around book of its kind ever published. It is a practical book for practical men, 
from the apprentice in the shop to the president in the office. It minutely describes and il- 
lustrates the most simole and yet the most efficient time and cost system yet devised. 2nd 
Revised and Enlarged Edition, just issued. 384 pages, 219 illustrations. Price . . . $5,00 

FUEL 

Combustion of Coal and the Prevention of Smoke. By Wm. M. Barr. 

This book has been prepared with special reference to the generation of heat by the com- 
bustion of the common fuels found in the United States, and deals particularly with the con- 
ditions necessary to the economic and smokeless combustion of bituminous coals in Stationary 
and Locomotive Steam Boilers. 

The' presentation of this important subject is systematic and progressive. The arrangement 
of the book is in a series of practical questions to which are appended accurate answers, which 
describe in language, free from technicalities, the several processes involved in the furnace 
combustion of American fuels; it clearly states the essential requisites for perfect combustion, 
and points out the best methods for furnace construction for obtaining the greatest quantity 
of heat from any given quality of coal. Nearly 350 pages, fully illustrated. Price . . $1.00 

Smoke Prevention and Fuel Economy. By Booth and Kershaw. 

A complete treatise for all interested in smoke prevention and combustion, being based on 
the German work of Ernst Schmatolla, but it is more than a mere translation of the German 
treatise, much being added. The authors show as briefly as possible the principles of fuel 
combustion, the methods which have been and are at present in use, as well as the proper 
scientific methods for obtaining all the energy in the coal and burning it without smoke. 
Considerable space is also given to the examination of the waste gases, and several of the 
reoresentative English and American mechanical stoker and similar appliances are described. 
The losses carried away in the waste gases are thoroughly analyzed and discussed in the Ap- 
pendix, and abstracts are also here given of various patents on combustion apparatus. The 
book is complete and contains much of value to all who have charge of large plants. 194 patros. 
Illustrated. Price $2.i0 



18 THE NORMAN W. HENLEY PUBLISHING CO. 

GAS ENGINES AND GAS 

Gas, Gasoline and Oil Engines. By Gardner D. Hiscox. Revised by 
Victor W. Page, M.E. 

Just issued New 1918 Edition, Revised and Enlarged. Every user of a gas engine needs 
this book. Simple, instructive and right up-to-date. The only complete work on the subject. 
Tells all about internal combustion engineering, treating exhaustively on the design, con- 
struction and practical application of all forms of gas, gasoline, kerosene and crude petroleum- 
oil engines. Describes minutely all auxiliary systems, such as lubrication, carburetion and 
ignition. Considers the theory and management of all forms of explosive motors for sta- 
tionary and marine work, automobiles, aeroplanes and motor-cycles. Includes also Producer 
Gas and Its Production. Invaluable instructions for all students, gas-engine owners, gas- 
engineers, patent experts, designers, mechanics, draftsmen and all having to do with the 
modern pewer. Illustrated by over 400 engravings, many specially made from engineering 
drawings, all in correct proportion. 650 pages, 435 engravings. Price .... $£.50 net 

The Gasoline Engine on the Farm: Its Operation, Repair and Uses. By 

Xeno W. Putnam. 

This is a practical treatise on the Gasoline and Kerosene Engine intended for the man who 
wants to know just how to manage his engine and how to apply it to all kinds of farm work 
to the best advantage. 

This book abounds with hints and helps for the farm and suggestions for the home and house- 
wife. There is so much of value in this book that it is impossible to adequately describe it 
in such small space. Suffice to say that it is the kind of a book every farmer will appreciate 
and every farm home ought to have. Includes selecting the most suitable engine for farm 
work, its most convenient and efficient installation, with chapters on troubles, their remedies, 
and how to avoid them. The care and management of the farm tractor in plowing, harrowing, 
harvesting and road grading are fully covered; also plain directions are given for handling 
the tractor on the road. Special attention is given to relieving farm life of its drudgery by 
applying power to the disagreeable small tasks which must otherwise be done by hand. Many 
home-made contrivances for cutting wood, supplying kitchen, garden, and barn with water, 
loading, hauling and unloading hay, delivering grain to the bins or the feed trough are in- 
cluded; also full directions for making the engine milk the cows, churn, wash, sweep the 
house and clean the windows, etc. Very fully illustrated with drawings of working parts and 
cuts showing Stationary, Portable and Tractor Engines doing all kinds of farm work. All 
money-making farms utilize power. Learn how to utilize power by reading the pages of this 
book. It is an aid to the result getter, invaluable to the up-to-date farmer, student, black- 
smith, implement dealer and, in fact, all who can apply practical knowledge of stationary 
gasoline engines or gas tractors to advantage. 530 pages. Nearly 180 engravings. Price $£.00 

WHAT IS SAID OF THIS BOOK: 

"Am much pleased with the book and find it to be very complete and up-to-date. I will 
heartily recommend it to students and farmers whom I think would stand in need of such a 
work, as I think it is an exceptionally good one." — N. S. Gardiner, Prof, in Charge, Clemson 
Agr. College of S. C; Dept. of Agri. and Agri. Exp. Station, Clemson College, S. C. 
"I feel that Mr. Putnam's book covers the main points which a farmer should know." — R. T. 
Burdick, Instructor in Agronomy, University of Vermont, Burlington, Vt. 

Gasoline Engines: Their Operation, Use and Care. By A. Hyatt Verrill. 

The simplest, latest and most comprehensive popular work published on Gasoline Engines, 
* ' describing what the Gasoline Engine is; its construction and operation; how to install it; 
how to select it; how to use it and how to remedy troubles encountered. Intended for Owners, 
Operators and Users of Gasoline Motors of all kinds. This work fully describes and illustrates the 
various types of Gasoline Engines used in Motor Boats, Motor Vehicles and Stationary Work. 
The parts, accessories and appliances are described with chapters on ignition, fuel, lubrication, 
operation and engine troubles. Special attention is given to the care, operation and repair 
of motors, with useful hints and suggestions on emergency repairs and makeshifts. A com- 
plete glossary of technical terms and an alphabetically arranged table of troubles and their 
symptoms form most valuable and unique features of this manual. Nearly every illustration 
in the book is original, having been made by the author. Every page is full of interest and 
value. A book which you cannot afford to be without. 275 pages, 152 specially made 
engravings. Price $1.50 

Gas Engine Construction, or How to Build a Half-horsepower Gas Engine. 

By Parsell and Weed. 

A practical treatise of 300 pages describing the theory and principles of the action of Gas 
Engines of various types and the design and construction of a half-horsepower Gas Engine, 
with illustrations of the work in actual progress, together with the dimensioned working draw- 
ings, giving clearly the sizes of the various details; for the student, the scientific investigator, 
and the amateur mechanic. This book treats of the subject more from the standpoint of 
practice than that of theory. The principles of operation of Gas Engines are clearly and 
simply described, and then the actual construction of a half-horsepower engine is taken up, 
step by step, showing in detail the making of the Gas Engine. 3rd Edition. 300 pages. 
Price .$2.50 



CATALOGUE OF GOOD, PRACTICAL BOOKS 19 



How to Run and Install Two- and Four-Cycle Marine Gasoline Engines. 

By C. Vox Culix. 

Revised and enlarged edition just issued. The object of this little book is to furnish a pocket 
instructor for the beginner, the busy man who uses an engine for pleasure or profit, but who 
does not have the time or inclination for a technical book, but simply to thoroughly under- 
stand how to properly operate, install and care for his own engine. The index refers to each 
trouble, remedy, and subject alphabetically. Being a quick reference to find the cause, remedy 
and prevention for troubles, and to become an expert with his own engine. Pocket size. 
Paper binding. Price 25 cents 

Modern Gas Engines and Producer Gas Plants. By R. E. jMathot. 

A guide for the gas engine designer, user, and engineer in the construction, selection, purchase, 
installation, operation, and maintenance of gas engines. More than one book on gas engines 
has been written, but not one has thus far even encroached on the field covered by this book. 
Above all, Mr. Mathot's work is a practical guide. Recognizing the need of a volume that 
would assist the gas engine user in understanding thoroughly the motor upon which he depends 
for power, the author has discussed his subject without the help of any mathematics and with- 
out elaborate theoretical explanations. Every part of the gas engine is described in detail, 
tersely, clearly, with a thorough understanding of the requirements of the mechanic. Help- 
ful suggestions as to the purchase of an engine, its installation, care, and operation, form a 
most valuable feature of the work. 320 pages, 175 detailed illustrations. Price . . . $2.50 

The Modern Gas Tractor. By Victor W. Page, M.E. 

A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Con- 
siders design and construction exhaustively, gives complete instructions for care, operation and 
repair, outlines all practical applications on the road and in the field. The best and latest 
work on farm tractors and tractor power plants. A work needed by farmers, students, black- 
smiths, mechanics, salesmen, implement dealers, designers and engineers. 2nd Edition, Re- 
vised. 504 pages, 228 illustrations, 3 folding plates. Price $2.00 

GEARING AND CAMS 

Bevel Gear Tables. By D. Ag. Engstrom. 

A book that will at once commend itself to mechanics and draftsmen. Does away with all 
the trigonometry and fancy figuring on bevel gears, and makes it easy for anyone to lay them 
out or make them just right. There are 36 full-page tables that show every necessary dimen- 
sion for all sizes or combinations you're apt to need. No puzzling, figuring or guessing. Gives 
placing distance, all the angles (including cutting angles), and the correct cutter to use. A 
copy of this prepares you for anything in the bevel-gear line. 3rd Edition. 66 pages. 
Price $1.00 

Change Gear Devices. By Oscar E. Perrigo. 

A practical book for every designer, draftsman, and mechanic interested in the invention and 
development of the devices for feed changes on the different machines requiring such mechanism. 
All the necessary information on this subject is taken up, analyzed, classified, sifted, and con- 
centrated for the use of busy men who have not the time to go through the masses of irrelevant 
matter with which such a subject is usually encumbered and select such information as will 
be useful to them. 
. It shows just what has been done, how it has been done, when it was done, and who did it. 
It saves time in hunting up patent records and re-inventing old ideas. 88 pages. 3rd Edition. 
Price $1.00 

Drafting of Cams. By Louis Rouillion. 

The laying out of cams is a serious problem unless you know how to go at it right. This puts 
you on the right road for practically any kind of cam you are likely to run up against. 3rd 
Edition. Price 25 Cents 

HYDRAULICS 

Hydraulic Engineering. By Gardner D. Hi^cox. 

A treatise on the properties, power, and resources of water for all purposes. Including the 
measurement of streams, the flow of water in pipes or conduits; the horsepower of falling water, 
turbine and impact water-wheels, wave motors, centrifugal, reciprocating and air-lift pumps. 
With 300 figures and diagrams and 36 practical tables. All who arc interested in water-works 
development will find this book a useful one, because it is an entirely practical treatise upon 
a subject of present importance and cannot fail in having a far-reaching influence, and for this 
reason should have a place in the working library of every engineer. Among the subjects 
treated are: Historical Hydraulics; Properties of Water; Measurement of the Flow of Streams; 



21 THE NORMAN W. HENLEY PUBLISHING CO. 

Flow from Sub-surface Orifices and Nozzles; Flow of Water in Pipes; Siphons of Various 
Kinds; Dams and Great Storage Reservoirs; City and Town Water Supply; Wells and Their 
Reinforcement; Air-lift Methods of Raising Water; Artesian Wells; Irrigation of Arid Dis- 
tricts; Water Power; Water Wheels; Pumps and Pumping Machinery; Reciprocating Pumps; 
Hydraulic Power Transmission; Hydraulic Mining; Canals; Ditches; Conduits and Pipe 
Lines; Marine Hydraulics; Tidal and Sea Wave Power, etc. 320 pages. Price . . . $4.00 

ICE AND REFRIGERATION 

Pocketbook of Refrigeration and Ice Making. By A. J. Wallis-Taylor. 

This is one of the latest and most comprehensive reference books published on the subject of 
refrigeration and cold storage. It explains the properties and refrigerating effect of the dif- 
ferent fluids in use, the management of refrigerating machinery and the construction and insu- 
lation of cold rooms with their required pipe surface for different degrees of cold; freezing 
mixtures and non-freezing brines, temperatures of cold rooms for all kinds of provisions, cold 
storage charges for all classes of goods, ice making and storage of ice, data and memoranda, 
for constant reference by refrigerating engineers, with nearly one hundred tables containing 
valuable references to every fact and condition required in the installment and operation of a 
refrigerating plant. New edition just published. Price $1.50 

INVENTIONS— PATENTS 

Inventors' Manual: How to Make a Patent Pay. 

This is a book designed as a guide to inventors in perfecting their inventions, taking out their 
patents and disposing of them. It is not in any sense a Patent Solicitor's Circular nor a Patent 
Broker's Advertisement. No advertisements of any description appear in the work. It is a 
book containing a quarter of a century's experience of a successful inventor, together with 
notes based upon the experience of many other inventors. 

Among the subjects treated in this work are: How to Invent. How to Secure a Good Patent. 
Value of Good Invention. How to Exhibit an Invention. How to Interest Capital. How 
to Estimate the Value of a Patent. Value of Design Patents. Value of Foreign Patents. 
Value of Small Inventions. Advice on Selling Patents. Advice on the Formation of Stock 
Companies. Advice on the Formation of Limited Liability Companies. Advice on Disposing 
of Old Patents. Advice as to Patent Attorneys. Advice as to Selling Agents. Forms of 
Assignments. License and Contracts. State Laws Concerning Patent Rights. 1900 Census 
of the United States by Counts of Over 10,000 Population. Revised Edition. 120 pages. 
Price $1.00 

KNOTS 

Knots, Splices and Rope Work. By A. Hyatt Verrill. 

This is a practical book giving complete and simple directions for making all the most useful 
and ornamental knots in common use, with chapters on Splicing, Pointing, Seizing, Serving, 
etc. This book is fully illustrated with 154 original engravings, which show how each knot, 
tie or splice is formed, and its appearance when finished. The book will be found of the greatest 
value to Campers, Yachtsmen, Travelers, Boy Scouts, in fact, to anyone having occasion to 
use or handle rope or knots for any purpose. The book is thoroughly reliable and practical, 
and is not only a guide, but a teacher. It is the standard work on the subject. Among the 
contents are: 1. Cordage, Kinds of Rope. Construction of Rope, Parts of Rope Cable and 
Bolt Rope. Strength of Rope, Weight of Rope. 2. Simple Knots and Bends. Terms Used 
in Handling Rope. Seizing Rope. 3. Ties and Hitches. 4. Noose, Loops and Mooring 
Knots. 5. Shortenings, Grommets and Salvages. 6. Lashings, Seizings and Splices. 7. 
Fancy Knots and Rope Work. 128 pages, 150 original engravings. 2nd Revised Edition. 

Price 75 cents 

LATHE WORK 

Lathe Design, Construction, and Operation, with Practical Examples of 
Lathe Work. By Oscar E. Perrigo. 

A new, revised edition, and the only complete American work on the subject, written by a 
man who knows not only how work ought to be done, but who also knows how to do it, and 
how to convey this knowledge to t)thers. It is strictly up-to-date in its descriptions and 
illustrations. Lathe history and the relations of the lathe to manufacturing are given; 
also a description of the various devices for feeds and thread-cutting mechanisms from early 
efforts in this direction to the present time. Lathe design is thoroughly discussed, includ- 
ing back gearing, driving cones, thread-cutting gears, and all the essential elements of the 
modern lathe. The classification of lathes is taken \ip, giving the essential differences of 
the several types of lathes including, as is usually understood, engine lathes, bench lathes, 
speed lathes, forge lathes, gap lathes, pulley lathes, forming lathes, multiple-spindle lathes, 
rapid-reduction lathes, precision lathes, turret lathes, special lathes, electrically driven lathes, 



CATALOGUE OF GOOD, PRACTICAL BOOKS 21 

etc. In addition to the complete exposition on construction and design, much practical 
matter on lathe installation, care and operation has been incorporated in the enlarged new 
edition. All kinds of lathe attachments for drilling, milling, etc., are described and com- 
plete instructions are given to enable the novice machinist to grasp the art of lathe operation 
as well as the principles involved in design. A number of difficult machining operations 
are described at length and illustrated. The new edition has nearly 500 pages and 350 illus- 
trations. Price $2.50 

TVHAT IS SAID OF THIS BOOK: 

"This is a lathe book from beginning to end, and is just the kind of a book which one de- 
lights to consult — a masterly treatment of the subject in hand." — Engineering Xeus. 
"This work will be of exceptional interest to any one who is interested in lathe practice, as 
one very seldom sees such a complete treatise on a subject as this is on the lathe." — Cana- 
dian Machinery. 

Practical Metal Turning. By Joseph G. Horxer. 

A work of 404 pages, fully illustrated, covering in a comprehensive manner the modern prac- 
tice of machining metal parts in the lathe, including the regular engine lathe, its essential 
design, its uses, its tools, its attachments, and the manner of holding the work and perform- 
ing the operations. The modernized engine lathe, its methods, tools and great range of accu- 
rate work. The turret lathe, its tools, accessories and methods of performing its functions. 
Chapters on special work, grinding, tool holders, speeds, feeds, modern tool steels, etc. 
Second edition $3.50 

Turning and Boring Tapers. By Fred H. Colvix. 

There are two ways to turn tapers; the right way and one other. This treatise has to do 
with the right way; it tells you how to start the work properly, how to set the lathe, what 
tools to use and how to use them, and forty and one other little things that you should know. 
Fourth edition 25 cents 

LIQUID AIR 

Liquid Air and the Liquefaction of Gases. By T. O' Conor Sloaxe. 

This book gives the history of the theory, discovery and manufacture of Liquid Air, and 

contains an illustrated description of all the experiments that have excited the wonder of 

audiences all over the country. It shows how liquid air, like water, is carried hundreds of 

miles and is handled in open buckets. It tells what may be expected from it in the near 

future. 

A book that renders simple one of the most perplexing chemical problems of the century. 

Startlinjg developments illustrated by actual experiments. 

It is not only a work of scientific interest and authority, but is intended for the general reader, 

being written in a popular style — easily understood by every one. Second edition. 365 

pages. Price , $3.00 

LOCOMOTIVE EXGINEERIXG 



Air-Brake Catechism. By Robert H. Blackall. 

This book is a standard text-book. It covers the Westinghouse Air-Brake Equipment, 
including the Xo. 5 and the No. 6 E.-T. Locomotive Brake Equipment; the K (Quick Ser- 
vice) Triple Valve for Freight Service; and the Cross-Compound Pump. The operation of 
all parts of the apparatus is explained in detail, and a practical way of finding their pecu- 
liarities and defects, with a proper remedy, is given. It contains 2,000 questions with their 
answers, which will enable any railroad man to pass any examination on the subject of 
Air Brakes. Endorsed and used by air-brake instructors and examiners on nearly every 
railroad in the United States. Twenty-sixth edition. 411 pages, fully illustrated with 
colored plates and diagrams. Price $2.00 

American Compound Locomotives. By Fred H. Colvtn. 

The only book on compounds for the engineman or shopman that shows in a plain, prac- 
tical way the various features of compound locomotives in use. Shows how they are made, 
vhat to do when they break down or balk. Contains sections as follows: A Bit of History. 
Theory of Compounding Steam Cylinders. Baldwin Two-Cylinder Compound. Pittsburg 
Two-Cylinder Compound. Rhose Island Compound. Richmond Compound. Rogers Com- 

Sjund. Schenectady Two-Cylinder Compound. Vauclain Compound. Tandem Compounds, 
aldwin Tandem. The Colvin-Witditman Tandem. Schenectady Tandem. Balanced 
Locomotives. Baldwin Balanced Compound. Plans for Balancing. Locating Blows. 
Breakdowns. Reducing Valves. Drifting. Valve Motion. Disconnecting. Power of Corn- 
round Locomotives. Practical Notes. 

Fu'ly illustrated and containing ten special "Duotone" inserts on heavy Plate Paper, show- 
ing different types of Compounds. 142 pages. Price $1.00 



22 THE NORMAN W. HENLEY PUBLISHING CO. 

Application of Highly Superheated Steam to Locomotives. By Robert 
Garbe. 

A practical book which cannot be recommended too highly to those motive-power men who 
are anxious to maintain the highest efficiency in their locomotives. Contains special chap- 
ters on Generation of Highly Superheated Steam; Superheated Steam and the Two-Cylinder 
Simple Engine; Compounding and Superheating; Designs of Locomotive Superheaters; 
Constructive Details of Locomotives Using Highly Superheated Steam. Experimental and 
"Working Results. Illustrated with folding plates and tables. Cloth. Price .... $2.50 

Combustion of Coal and the Prevention of Smoke. By Wm. M. Barr. 

This book has been prepared with special reference to the generation of heat by the com- 
bustion of the common fuels found in the United States and deals particularly with the 
conditions necessary to the economic and smokeless combustion of bituminous coal in Sta- 
tionary and Locomotive Steam Boilers. 

Presentation of this important subject is systematic and progressive. The arrangement of 
the book is in a series of practical questions to which are appended accurate answers, which 
describe in language free from technicalities the several processes involved in the furnace 
combustion of American fuels; it clearly states the essential requisites for perfect combus- 
tion, and points out the best methods of furnace construction for obtaining the greatest 
quantity of heat from any given quality of coal. Nearly 350 pages, fully illustrated. 
Price $1.00 

Diary of a Round-House Foreman. By T. S. Reilly. 

This is the greatest book of railroad experiences ever published. Containing a fund of in- 
formation and suggestions along the line ,of handling men, organizing, etc., that one cannot 
afford to miss. 176 pages. Price .$1.00 

Link Motions, Valves and Valve Setting. By Fred H. Colvin, Associate Editor 
of "American Machinist." 

A handy book for the engineer or machinist that clears up the mysteries of valve setting. 
Shows the different valve gears in use, how they work, and why. Piston and slide valves 
of different types are illustrated and explained. A book that every railroad man in the 
motive-power department ought to have. Contains chapters on Locomotive Link Motion, 
Valve Movements, Setting Slide Valves, Analysis by Diagrams, Modern Practice, Slip of 
Block, Slice Valves, Piston Valves, Setting Piston Valves, Joy-Allen Valve Gear, Walschaert 
Valve Gear, Gooch Valve Gear, Alfree-Hubbell Valve Gear, etc., etc. Fully illustrated. 

P«ce 50 cents 

Locomotive Boiler Construction. By Frank A. Kleinhans. 

The construction of boilers in general is treated and, following this, the locomotive boiler 
is taken up in the order in which its various parts go through the shop. Shows all types 
of boilers used; gives details of construction; practical facts, such as life of riveting, punches 
and dies; work done per day, allowance for bending and flanging sheets and other data. 
Including the recent Locomotive Boiler Inspection Laws and Examination Questions with 
their answers for Government Inspectors. Contains chapters on Laying-Out Work; Flang- 
ing and Forging; Punching; Shearing; Plate Planing; General Tables; Finishing Parts; 
Bending; Machinery Parts; Riveting; Boiler Details; Smoke-Box Details; Assembling 
and Calking; Boiler-Shop Machinery, etc., etc. 

There isn't a man who has anything to do with boiler work, either new or repair work, who 
doesn't need this book. The manufacturer, superintendent, foreman and boiler worker — 
all need it. No matter what the type of bioler, you'll find a mint of information that you 
wouldn't be without. Over 400 pages, five large folding plates. Price $3.00 

Locomotive Breakdowns and their Remedies. By Geo. L. Fowler. Re- 
vised by Wm. W. Wood, Air-Brake Instructor. Just issued. Revised pocket 
edition. 

It is out of the question to try and tell you about every subject that is covered in this pocket 
edition of Locomotive Breakdowns. Just imagine all the common troubles that an engineer 
may expect to happen some time, and then add all of the unexpected ones, troubles that could 
occur, but that you have never thought about, and you will find that they are all treated with 
the very best methods of repair. Walschaert Locomotive Valve Gear Troubles, Electric 
Headlight Troubles, as well as Questions and Answers on the Air Brake are all included. 312 
pages. 8th Revised Edition. Fully illustrated. Price $1.00 

Locomotive Catechism. By Robert Grimshaw. 

The revised edition of "Locomotive Catechism," by Robert Grimshaw, is a New Book from 
Cover to Cover. It contains twice as many pages and double the number of illustrations of 
previous editions. Includes the greatest amount of practical information ever published on 
the construction and management of modern locomotives. Specially Prepared Chapters on 
the Walschaert Locomotive Valve Gear, the Air-Brake Equipment and the Electric Headlight 
are given. 



CATALOGUE OF GOOD, PRACTICAL BOOKS 23 

It commends itself at once to every Engineer and Fireman, and to all who are going in for 
examination or promotion. In plain language, with full, complete answers, not only all the 
questions asked by the examining engineer are given, but those which the young and less 
experienced would ask the veteran, and which old hands ask as "stickers.'' It is a veritable 
Encyclopedia of the Locomotive, is entirely free from mathematics, easily understood and 
thoroughly up to date. Contains over 4,000 Examination Questions with their Answers. 
825 pages, 437 illustrations, and 3 folding plates. 28th Revised Edition. Price S3. 50 

Practical Instructor and Reference Book for Locomotive Firemen and 
Engineers. By Chas. F. Lockhart. 

An entirely new book on the Locomcmve. It appeals to every railroad man, as it tells him 
how things are done and the right way to do them. Written by a man who has had years of 
practical experience in locomotive shops and on the road firing and running. The information 
given in this book cannot be found in any other similar treatise. Eight hundred and fifty-one 
questions with their answers are included, which will prove specially helpful to those preparing 
for examination. Practical information on: The Construction and Operation of Locomotives, 
Breakdowns and their Remedies, Air Brakes and Valve Gears. Rules and Signals are handled 
in a thorough manner. As a book of reference it cannot be excelled. The book is divided 
into six parts, as follows: 1. The Fireman's Duties. 2. General Description of the Locomotive. 
3. Breakdowns and their Remedies. 4. Air Brakes. 5. Extracts from Standard Rules. 
6. Questions for Examination. The 851 questions have been carefully selected and arranged. 
These cover the examinations required by the different railroads. 368 pages, 88 illustrations. 
Price : §1.50 

Prevention of Railroad Accidents, or Safety in Railroading. By George 
Bradshaw. 

This book is a heart-to-heart talk with Railroad Employees, dealing with facts, not theories, 
and showing the men in the ranks, from every-day experience, how accidents occur and how 
they may be avoided. The book is illustrated with seventy original photographs and drawings 
showing the safe and unsafe methods of work. No visionary schemes, no ideal pictures. 
Just Plain Facts and Practical Suggestions are given. Every railroad employee who reads the 
book is a better and safer man to have in railroad service. It gives just the information which 
will be the means of preventing many injuries and deaths. All railroad employees should 
procure a copy, read it, and do their part in preventing accidents. 169 pages. Pocket size. 
Fully illustrated. Price 5() cents 

Train Rule Examinations Made Easy. By G. E. Collingwood. 

This is the only practical work on train rules in print. Every detail is covered, and puzzling 
points are explained in simple, comprehensive language, making it a practical treatise for the 
Train Dispatcher, Engineman, Trainman, and all others who have to do with the movements 
of trains. Contains complete and reliable information of the Standard Code of Train Rules 
for single track. Shows Signals in Colors, as used on the different roads. Explains fully the 
practical application of train orders, giving a clear and definite understanding of all orders 
which may be used. The meaning and necessity for certain rules are explained in such a 
manner that the student may know beyond a doubt the rights conferred under any orders he 
may receive or the action required by certain rules. As nearly all roads require trainmen to 
pass regular examinations, a complete set of examination questions, with their answers, are 
included. These will enable the student to pass the required examinations with credit to 
himself and the road for which he works. 2nd Edition, Revised. 256 pages, fully illustrated, 
with Train Signals in Colors. Price SI. 35 

The Walschaert and Other Modern Radial Valve Gears for Locomotives. 

By Wm. W. Wood. 

If you would thoroughly understand the "Walschaert Valve Gear you should possess a copy 
of this book, as the author takes the plainest form of a steam engine — a stationary engine in 
the rough, that will only turn its crank in one direction — and from it builds up, with the read- 
er's help, a modern locomotive equipped with the Walschaert Valve Gear, complete. The 
points discussed are clearly illustrated: Two large folding plates that show the positions of 
the valves of both inside or outside admission type, as well as the links and other parts of the 
gear when the crank is at nine different points in its revolution, are especially valuable in mak- 
ing the movement clear. These employ sliding cardboard models which are contained in a 
?ocket in the cover, 
'he book is divided into five general divisions, as follows: 1. Analysis of the gear. 2. De- 
signing and erecting the gear. 3. Advantages of the gear. 4. Questions and answers relating 
to the Walschaert Valve Gear. 5. Setting valves with the Walschaert Valve Gear; the three 
primary types of locomotive valve motion; modern radial valve gears other than the Wal- 
schaert; the Hobart All-free Valve and Valve Gear, with questions and answers on breakdowns; 
the Baker-Pilliod Valve Gear; the Improved Baker-Pilliod Valve Gear, with questions and 
answers on breakdowns. 

The questions with full answers given will be especially valuable to firemen and engineers in 
preparing for an examination for promotion. 245 pages. 3rd Revised Edition. Price $1.50 



24 THE NORMAN W. HENLEY PUBLISHING CO 



Westinghouse E-T Air-Brake Instruction Pocket Book. 

Air-Brake Instructor. 



By Wm. W. Wood, 



Here is a book for the railroad man, and the man who aims to be one. It is without doubt 
the only complete work published on the Westinghouse E-T Locomotive Brake Equipment. 
Written by an Air-Brake Instructor who knows just what is needed. It covers the subject 
thoroughly. Everything about the New Westinghouse Engine and Tender Brake Equip- 
ment, including the standard No. 5 and the Perfected No. 6 style of brake, is treated in detail. 
Written in plain English and profusely illustrated with Colored Plates, which enable one to 
trace the flow of pressures throughout the entire equipment. The best book ever published 
on the Air Brake. Equally good for the beginner and the advanced engineer. Will pass any 
one through any examination. It informs and enlightens you on every point. Indispensable 
to every engineman and trainman. N 

Contains examination questions and answers on the E-T equipment. Covering what the E-T 
Brake is. How it should be operated. What to do when defective. Not a question can be 
asked of the engineman up for promotion, on either the No. 5 or the No. 6 E-T equipment, 
that is not asked and answered in the book. If you want to thoroughly understand the E-T 
equipment get a copy of this book. It covers every detail. Makes Air-Brake troubles and 
examinations easy. Price §1.50 

MACHINE-SHOP PRACTICE 



American Tool Making and Interchangeable Manufacturing. By J. V. 

WOODWORTH. 

A "shoppy" book, containing no theorizing, no problematical or experimental devices. There 
are no badly proportioned and impossible diagrams, no catalogue cuts, but a valuable collec- 
tion of drawings and descriptions of devices, the rich fruits of the author's own experience. 
In its 500-odd pages the one subject only, Tool Making, and whatever relates thereto, is dealt 
with. The work stands without a rival. It is a complete, practical treatise, on the art of 
American Tool Making and system of interchangeable manufacturing as carried on to-day in 
the United States. In it are described and illustrated all of the different types and classes of 
small tools, fixtures, devices, and special appliances which are in general use in all machine- 
manufacturing and metal-working establishments where economy, capacity, and interchange- 
ability in the production of machined metal parts are imperative. The science of jig making 
is exhaustively discussed, and particular attention is paid to drill jigs, boring, profiling and 
milling fixtures and other devices in which the parts to be machined are located and fastened 
within the contrivances. All of the tools, fixtures, and devices illustrated and described have 
been or are used for the actual production of work, such as parts of drill presses, lathes, patented 
machinery, typewriters, electrical apparatus, mechanical appliances, brass goods, composition 
parts, mould products, sheet-metal articles, drop-forgings, jewelry, watches, medals, coins, etc. 
531 pages. Price $4.00 

HENLEY'S ENCYCLOPEDIA OF PRACTICAL ENGINEERING AND ALLIED 
TRADES. Edited by Joseph G. Horner, A.M.I., M.E. 

This set of five volumes contains about 2,500 pages with thousands of illustrations, including 
diagrammatic and sectional drawings with full explanatory details. This work covers the 
entire practice of Civil and Mechanical Engineering. The best known experts in all branches 
of engineering have contributed to these volumes. The Cyclopedia is admirably well adapted 
to the needs of the beginner and the self-taught practical man, as well as the mechanical 
engineer, designer, draftsman, shop superintendent, foreman, and machinist.^ The work will 
be found a means of advancement to any progressive man. It is encyclopedic in scope, thor- 
ough and practical in its treatment on technical subjects, simple and clear in its descriptive 
matter, and without unnecessary technicalities or formulae. The articles are as brief as may 
be and yet give a reasonably clear and explicit statement of the subject, and are written by 
men who have had ample practical experience in the matters of which they write. It tells 
* you all you want to know about engineering and tells it so simply, so clearly, so concisely, that 
one cannot help but understand. As a work of reference it is without a peer. Complete 
set of five volumes, price §25.00 

The Modern Machinist. By John T. Usher. 

This is a book, showing by plain description and by profuse engravings made expressly for 
the work, all that is best, most advanced, and of the highest efficiency in modern machine- 
shop practice, tools and implements, showing the way by which and through which, as Mr. 
Maxim says, "American machinists have become and are the finest mechanics in the world." 
Indicating as it does, in every line, the familiarity of the author with every detail of daily 
experience in the shop, it cannot fail to be of service to any man practically connected with 
the shaping or finishing of metals. 

There is nothing experimental or visionary about the book, all devices being in actual use 
and giving good results. It might be called a compendium of shop methods, showing a 
variety of special tools and appliances which will give new ideas to many mechanics, from 
the superintendent down to the man at the bench. It will be found a valuable addition to 
any machinist's library, and should be consulted whenever a new or difficult job is to be 
done, whether it is boring, milling, turning, or planing, as they are all treated in a practical 
manner. Fifth edition. 320 pages. 250 illustrations. Price $2.50 



L 



CATALOGUE OF GOOD, PRACTICAL BOOKS 25 



THE WHOLE FIELD OF MECHANICAL MOVEMENTS 
COVERED BY MR. HISCOX'S TWO BOOKS 

We publish two books by Gardner D. Hiscox that will keep you from "inventing" things that hate 
been done before, and suggest ways of doing things that you. have not thought of before. Many a 
man spends time and money . pondering over some mechanical problem, only to learn, after he 
has solved the problem, that the same thing has been accomplished and put in practice by others 
long before. Time and money spent in an effort to accomplish what has already been accomplished 
are time and money LOST. The whole field of mechanics, every known mechanical movement, 
and practically every device are covered by these two books. If the thing you want has been invented, 
it is illustrated in them. If it hasn't been invented, then you'll find in them the nearest things 
to what you want, some movements or devices that will apply in your case, perhaps; or which 
will give you a key from which to work. No book or set of books ever published is of more real 
value to the Inventor, Draftsman, or practical Mechanic than the two volumes described below. 

Mechanical Movements, Powers, and Devices. By Gardner D. Hiscox. 

This is a collection of 1,890 engravings of different mechanical motions and appliances, ac- 
companied by appropriate text, making it a book of great value to the inventor, the drafts- 
man, and to all readers with mechanical tastes. The book is divided into eighteen sections 
or chapters, in which the subject-matter is classified under the following heads: Mechanical 
Powers; Transmission of Power; Measurement of Power; Steam Power; Air Power Appli- 
ances; Electric Power and Construction; Navigation and Roads; Gearing; Motion and 
Devices; Controlling Motion; Horological; Mining; Mill and Factory Appliances; Con- 
struction and Devices; Drafting Devices; Miscellaneous Devices, etc. loth Edition. 400 
octavo pages. Price $3.00 

Mechanical Appliances, Mechanical Movements and Novelties of Construc- 
tion. By Gardner D. Hiscox. 

This is a supplementary volume to the one upon mechanical movements. Unlike the first 
volume, which is more elementary in character, this volume contains illustrations and de- 
scriptions of many combinations of motions and of mechanical devices and appliances found 
in different lines of machinery, each device being shown by a line drawing with a description 
showing its working parts and the method of operation. From the multitude of devices de- 
scribed and illustrated might be mentioned, in passing, such items as conveyors and elevators, 
Pony brakes, thermometers, various types of boilers, solar engines, oil-fuel burners, condensers, 
evaporators, Corliss and other valve gears, governors, gas engines, water motors of various 
descriptions, air ships, motors and dynamos, automobile and motor bicycles, railway lock 
signals, car couplers, link and gear motions, ball bearings, breech-block mechanism for heavy 
guns, and a laree accumulation of others of equal importance. One thousand specially made 
engravings. 396 octavo pages. Fourth edition. Price 83.00 

Machine-Shop Tools and Shop Practice. By W. H. Vandervoort. 

A work of 555 pages and 673 illustrations, describing in every detail the construction, opera 
tion and manipulation of both hand and machine tools. Includes chapters on filing, fit- 
ting and scraping surfaces; on drills, reamers, taps and dies; the lathe and its tools: planers,, 
shapers, and their tools; milling machines and cutters; gear cutters and gear cutting; drill- 
ing machines and drill work; grinding machines and their work; hardening and tempering; 
gearing, belting and transmission machinery; useful data and tables. Sixth edition. 
Price |3.00 

Machine-Shop Arithmetic. By Colvin-Cheney. 

This is an arithmetic of the things you have to do with daily. It tells you plainly about: 
how to find areas in figures; how to find surface or volume of balls or spheres; handy ways 
for calculating; about compound gearing; cutting screw threads on any lathe; drilling for 
taps; speeds of drills; taps, emery wheels, grindstones, milling cutters, etc.; all about the 
Metri" system with conversion tables; properties of metals; strength of bolts and nuts; 
decimal equivalent of an inch. All sorts of machine-shop fitmrinsi and 1,001 other things, 
any one of which ought to be worth more than the price of this book to you, as it saves you 
the trouble of bothering the boss. 6th Edition. 131 pages. Price 50 Cents 

Modern Machine-Shop Construction, Equipment and Management. By 

Oscar E. Perrigo. 

The only work published that describes the Modern Shop or Manufacturing Plant from the 
time the grass is growinn on the site intended for it until the finished product is shipped. Just 
the book needed by those contemplating the erection of modern shop buildings, the rebuilding 
and reorganization of old ones, or the introduction of Modern Shop Methods, time and cost 
systems. It is a book written and illustrated by a practical shop man for practical shop men 
who are too busy to read theories and want facts. It is the most complete all-round book of 
its kind ever published. Second Edition, He vised. 384 large quarto pages. 219 original and 
specially made illustrations. 2nd Revised and Enlarged Edition. Price $5.00 



26 



THE NORMAN W. HENLEY PUBLISHING CO 



Modern Milling Machines: Their Design, Construction, and Operation. 

By Joseph G. Horner. 

This book describes and illustrates the Milling Machine and its work in such a plain, clear 
and forceful manner, and illustrates the subject so clearly and completely, that the up-to- 
date machinist, student or mechanical engineer cannot afford to do without the valuable 
information which it contains. It describes not only the early machines of this class, but notes 
their gradual development into the splendid machines of the present day, giving the design 
and construction of the various types, forms, and special features produced by prominent 
manufacturers, American and foreign. 304 pages, 300 illustrations. Cloth. Price . . . $4.00 

6< Shop Kinks." By Robert Grimshaw. 

A book of 400 pages and 222 illustrations, being entirely different from any other book on 
machine-shop practice. Departing from conventional style, the author avoids universal 
or common shop usage and limits his work to showing special ways of doing things better, 
more cheaply and more rapidly than usual. As a result the advanced methods of represen- 
tative establishments of the world are placed at the disposal of the reader. This book shows 
the proprietor where large savings are possible, and how products may be improved. To 
the employee it holds out suggestions that, properly applied, will hasten his advancement. 
No shop can afford to be without it. It bristles with valuable wrinkles and helpful sugges- 
tions. It will benefit all, from apprentice to proprietor. Every machinist, at any age, should 
study its pages. Fifth edition. Price , $2.50 

Threads and Thread Cutting. By Colvin and Stabel. 

This clears up many of the mysteries of thread-cutting, such as double and triple threads, 
internal threads, catching threads, use of hobs, etc. Contains a lot of useful hints and several 
tables. Third edition. Price 25 Cents 



MANUAL TRAINING 

Economics of Manual Training. By Louis Rouillion. 

The only book published that gives just the information needed by all interested in Manual 
Training, regarding Buildings, Equipment, and Supplies. Shows exactly what is needed 
for all grades of the work from the Kindergarten to the High and Normal School. Gives 
itemized lists of everything used in Manual Training Work and tells just what it ought to 
cost. Also shows where to buy supplies, etc. Contains 174 pages, and is fully illustrated. 
Second edition. Price $1.50 



MARINE ENGINEERING 

The Naval Architect's and Shipbuilder's Pocket Book of Formulae, Rules, 
and Tables and Marine Engineer's and Surveyor's Handy Book of 
Reference. By Clement Mackrow and Lloyd Woollard. 

The eleventh Revised and Enlarged Edition of this most comprehensive work has just been 
issued. It is absolutely indispensable to all engaged in the Shipbuilding Industry, as it con- 
denses into a compact form all data and formulae that are ordinarily required. The book is 
completely up to date, including among other subjects a section on Aeronautics. 750 pages, 
limp leather binding. Price $5.00 net 



Marine Engines and Boilers: Their Design and Construction. 

Bauer, Leslie S. Robertson and S. Bryan Donkin. 



By Dr. G 



In the words of Dr. Bauer, the present work owes its origin to an oft felt want of a condensed 
treatise embodying the theoretical and prac-fical rules used in designing marine engines and 
boilers. The need of such a work has been felt by most engineers engaged in the construction 
and working of marine engines, not only by the younger men, but also by those of greater ex- 
perience. The fact that the original German work was written by the chief engineer of the 
famous Vulcan Works, Stettin, is in itself a guarantee that this book is in all respects thor- 
oughly up-to-date, and that it embodies all the information which is necessary for the design 
and construction of the highest tyDes of marine engines and boilers. It may be said that the 
motive power which Dr. Bauer has placed in the fast German liners that have been turned out 
of late years from the Stettin Works reoresent the very best practice in marine engineering of 
the present day. The work is clearlv written, thoroughly systematic, theoretically sound; 
while the character of the plans, drawings, tables, and statistics is without reproach. The 
illustrations are careful reproductions from actual working drawings, with some well- executed 
photographic views of completed engines and boilers. 744 pages, 550 illustrations and num- 
erous tables. Cloth. Price $9.00 net 



CATALOGUE OF GOOD, PRACTICAL BOOKS 27 

, MINING 

Ore Deposits, with a Chapter on Hints to Prospectors. By J. P. Johnson. 

This book gives a condensed account of the ore deposits at present known in South Africa. 
It is also intended as a guide to the prospector. Only an elementary knowledge of geology 
and some mining experience are necessary in order to understand this work. With these 
qualifications, it will materially assist one in his search for metalliferous mineral occurrences 
and, so far as simple ores are concerned, should enable one to form some idea of the possi- 
bilities of any he may find. Illustrated. Cloth. Price $2-00 

Practical Coal Mining. By T. H. Cockin. 

An important work, containing 428 pages and 213 illustrations, complete with practical details, 
which will intuitively impart to the reader not only a general knowledge of the principles 
of coal mining, but also considerable insight into allied subjects. The treatise is positively 
up-to-date in every instance, and should be in the hands of every colliery engineer, geologist, 
mine operator, superintendent, foreman, and all others who are interested in or connected with 
the industry. 3d Edition. Cloth. Price $2.50 

Physics and Chemistry of Mining. By T. H. Byrom. 

A practical work for the use of all preparing for examinations in mining or qualifying for 
colliery managers' certificates. The aim of the author in this excellent book is to place clearly 
before the reader useful and authoritative data which will render him valuable assistance in 
his studies. The only work of its kind published. The information incorporated in it will 
prove of the greatest practical utility to students, mining engineers, colliery managers, and 
all others who are specially interested in the present-day treatment of mining problems. 160 
pages, illustrated. Price $2.00 

PATTERN MAKING 

Practical Pattern Making. By F. W. Barrows. 

This book, now in its second edition, is a comprehensive and entirely practical treatise on the 
subject of pattern making, illustrating pattern work in both wood and metal, and with definite 
instructions on the use of plaster of paris in the trade. It gives specific and detailed descrip- 
tions of the materials used by pattern makers, and describes the tools, both those for the 
bench and the more interesting machine tools, having complete chapters on the Lathe, the 
Circular Saw, and the Band Saw. It gives many examples of pattern work, each one fully 
illustrated and explained with much detail. These examples, in their great variety, offer much 
that will be found of interest to all pattern makers, and especially to the younger ones, who 
are seeking information on the more advanced branches of their trade. 

In this second edition of the work will be found much that is new, even to those who have 
long practised this exacting trade. In the description of patterns as adapted to the Moulding 
Machine many difficulties which have long prevented the rapid and economical production of 
castings are overcome; and this great, new branch of the trade is given much space. Strip- 
ping plate and stool plate work and the less expensive vibrator, or rapping plate work, are 
all explained in detail. 

Plain, every-day rules for lessening the cost of patterns, with a complete system of cost 
keeping, a detailed method of marking, applicable to all branches of the trade, with com- 
plete information showing what the pattern is, its specific title, its cost, date of production, 
material of which it is made, the number of pieces and core-boxes, and its location in the 
pattern safe, all condensed into a most complete card record, with cross index. 
The book closes with an original and practical method for the inventory and valuation of 
patterns. Containing nearly 350 pages and 170 illustrations. Price $3.00 

PERFUMERY 



Perfumes and Cosmetics: Their Preparation and Manufacture. By G. W. 
AsKiNSONj Perfumer. 

A comprehensive treatise, in which there has been nothing omitted that could be of value 
to the perfumer or manufacturer of toilet preparations. Complete directions for making 
handkerchief perfumes, smelling-salts, sachets, fumigating pastilles; preparations for the 
care of the skin, the mouth, the hair, cosmetics, hair dyes and other toilet articles are given, 
also a detailed description of aromatic substances; their nature, tests 6f purity, and whole- 
some manufacture, including a chapter on synthetic products, with formulas for their use. 
A book of general as well as professional interest, meeting t he wants not only of the drug- 
gist and perfume manufacturer, but also of the general public. Among the contents are: 
1. The History of Perfumery. 2. About Aromatic Substances in General. 3. Odors from 
the Vegetable Kingdom. 4. The Aromatic Vegetable Substances Employed in Perfumery. 
5. The Animal Substances Used in Perfumery. 6. The Chemical Products Used in Perfumery. 
7. The Extraction of Odors. 8. The Special Characteristics of Aromatic Substances. 9. The 
Adulteration of Essential Oils and Their Recognition. 10. Synthetic Products. 11. Table 
of Physical Properties of Aromatic Chemicals. 12. The Essences or Extracts Employed 
in Perfumery. 13. Directions for Making the Most Important Essences and Extracts. 



28 THE NORMAN W. HENLEY PUBLISHING CO. 

14. The Division of Perfumery. 15. The Manufacture of Handkerchief Perfumes. 16. For- 
mulas for Handkerchief Perfumes. 17. Ammoniacal and Acid Perfumes. #8. Dry Per- 
fumes. 19. Formulas for Dry Perfumes. 20. The Perfumes Used for Fumigation. 21. An- 
tiseptic and Therapeutic Value of Perfumes. 22. Classification of Odors. 23. Some Special 
Perfumery Products. 24. Hygiene and Cosmetic Perfumery. 25. Preparations for the Care 
of the Skin. 26. Manufacture of Casein. 27. Formulas for Emulsions. 28. Formulas for 
Cream. 29. Formulas for Meals, Pastes and Vegetable Milk. 30. Preparations Used for 
the Hair. 31. Formulas for Hair Tonics and Restorers. 32. Pomades and Hair Oils. 
33. Formulas for the Manufacture of Pomades and Hair Oils. 34. Hair Dyes and Depila- 
tories. 35. Wax Pomades, Bandolines and Brillian tines. 36. Skin Cosmetics and 
Face Lotions. 37. Preparations for the Nails. 38. Water Softeners and Bath Salts. 39. 
Preparations for the Care of the Mouth. 40. The Colors Used in Perfumery. 41. The Uten- 
sils Used in the Toilet. Fourth edition, much enlarged and brought up to date. Nearly 
400 pages, illustrated. Price $5.00 

WHAT IS SAID OF THIS BOOK: 

"The most satisfactory work on the subject of Perfumery that we have ever seen." 
"We feel safe in saying that here is a book on Perfumery that will not disappoint you, for 
it has practical and excellent formulae that are within your ability to prepare readily." 
"We recommend the volume as worthy of confidence, and say that no purchaser will be dis- 
appointed in securing from its pages good value for its cost, and a large dividend on the same, 
even if he should use but one per cent, of its working formulas. There is money in it for every 
user of its information." — Pharmaceutical Record. 

PLUMBING 



Mechanical Drawing for Plumbers. By R. M. Starbuck. 

A concise, comprehensive and practical treatise on the subject of mechanical drawing in its 
various modern applications to the work of all who are in any way connected with the plumb- 
ing trade. Nothing will so help the plumber in estimating and in explaining work to cus- 
tomers and workmen as a knowledge of drawing, and to the workman it is of inestimable 
value if he is to rise above his position to positions of greater responsibility. Among the 
chapters contained are: 1. Value to plumber of knowledge of drawing; tools required and 
their use; common views needed in mechanical drawing. 2. Perspective versus mechanical 
drawing in showing plumbing construction. 3. Correct and incorrect methods in plumbing 
drawing; plan and elevation explained. 4. Floor and cellar plans and elevation; scale 
drawings; use of triangles. 5. Use of triangles; drawing of fittings, traps, etc. 6. Drawing 
plumbing elevations and fittings. 7. Instructions in drawing plumbing elevations. 8. The 
drawing of plumbing fixtures; scale drawings. 9. Drawings of fixtures and fittings. 10. Ink- 
ing of drawings. 11. Shading of drawings. 12. Shading of drawings. 13. Sectional drawings; 
drawing of threads. 14. Plumbing elevations from architect's plan. 15. Elevations of sepa- 
rate parts of the plumbing system. 16. Elevations from the architect's plans. 17. Drawings 
of detail plumbing connections. 18. Architect's plans and plumbing elevations of residence. 
19. Plumbing elevations of residence (continued) ; plumbing plans for cottage. 20. Plumbing 
elevations; roof connections. 21. Plans and plumbing elevations for six-flat building. 22. 
Drawing of various parts of the plumbing system; use of scales. 23. Use of architect's scales. 
24. Special features in the illustrations of country plumbing. 25. Drawing of wrought-iron 
piping, valves, radiators, coils, etc. 26. Drawing of piping to illustrate heating systems. 
150 illustrations. Price $1.50 

Modern Plumbing Illustrated. By R. M. Starbuck. 

This book represents the highest standard of plumbing work. It has been adopted and used 
as a reference book by the United States Government in its sanitary work in Cuba, Porto 
Pico and the Philippines, and by the principal Boards of Health of the United States and 
Canada. 

It gives connections, sizes and working data for all fixtures and groups of fixtures. It is help- 
ful to the master plumber in demonstrating to his customers and in figuring work. It gives 
the mechanic and student quick and easy access to the best modern plumbing practice. Sug- 
gestions for estimating plumbing construction are contained in its pages. This book repre- 
sents, in a word, the latest and best up-to-date practice and should be in the hands of every 
architect, sanitary engineer and plumber who wishes to keep himself up to the minute on 
this important feature of construction. Contains following chapters, each illustrated with a 
full-page plate: Kitchen sink, laundry tubs, vegetable wash sink; lavatories, pantry sinks, 
contents of marble slabs; bath tub, foot and sitz bath, shower bath; water closets, venting 
of water closets; low-down water closets, water closets operated by flush valves, water closet 
range; slop sink, urinals, the bidet; hotel and restaurant sink, grease trap; refrigerators, 
safe wastes, laundry waste, lines of refrigerators, bar sinks, soda fountain sinks; horse stall, 
frost-proof water closets; connections for S traps, venting; connections for drum traps; 
soil-pipe connections; supporting of soil pipe; main trap and fresh-air inlet; floor drains and 
cellar drains, subsoil drainage; water closets and floor connections; local venting; connections 
for bath rooms; connections for bath rooms, continued; examples of poor practice; roughing 
work ready foV test; testing of plumbing systenfs; method of continuous venting; continuous 
venting for two-floor work; continuous venting for two lines of fixtures on three or more 
floors; continuous venting of water closets; plumbing for cottage house; construction for 
cellar piping; plumbing for residence, use of special fittings; plumbing for two-flat house; 
plumbing for apartment building, plumbing for double apartment building; plumbing for 
office building; plumbing for public toilet rooms; plumbing for public toilet rooms, con- 
tinued; plumbing for bath establishment; plumbing for engine house, factory plumbing; 
automatic flushing for schools, factories, etc.; use of flushing valves; urinals for public toilet 
rooms; the Durham system, the destruction of nines bv electro! vsis; construction of work 



CATALOGUE OF GOOD, PRACTICAL BOOKS 29 

without use of lead; automatic sewage lift; automatic sump tank; country plumbing; 
construction of cesspools; septic tank and automatic sewage siphon; water supply for 
country house; thawing of water mains and service by electricity; double boilers; hot 
water supply of large buildings; automatic control of hot-water tank; suggestions for 
estimating plumbing construction. 407 octavo pages, fully illustrated by 57 full-page 
engravings. Third, revised and enlarged edition, just issued. Price $4.00 

Standard Practical Plumbing. By R. M. Starbuck. 

A complete practical treatise of 450 pages, covering the subject of Moderr Plumbing in aV> its 
branches, a large amount of space being devoted to a very compete and practical treatmer: of 
the subject of Hot Water Supply and Circulation and Range Boiier Work. Its thirty charters 
include about every phase of the subject one can think of, making it an indispensable work to 
the master plumber, the journeyman plumber, and the apprentice plumber, containing «:h.p.p- 
ters on: the plumber's tools; wiping solder; composition and use; joint wiping; lead work; 
traps; siphonage of traps; venting; continuous venting; house sewer and sewer connections; 
house drain; soil piping, roughing; main trap and fresh air inlet; floor, yard, cellar drains, 
rain leaders, etc.; fixture wastes; water closets; ventilation; improved plumbing connections; 
residence plumbing; plumbing for hotels, schools, factories, stables, etc.; modern country 
plumbing; filtration of sewage and water supply; hot and cold supply; range boilers; circula- 
tion; circulating pipes; range boiler problems; hot water for large buildings; water lift and 
its use; multiple connections for hot water boilers; heating of radiation by supply system; 
theory for the plumber; drawing for the plumber. Fully illustrated by 347 engravings. 
Price $3.00 

RECIPE BOOK 

Henley's Twentieth Century Book of Recipes, Formulas and Processes. 

Edited by Gardner D. Hiscox. 

The most valuable Techno-chemical Formula Book published, including over 10,000 selected 
scientific, chemical, technological, and practical recipes and processes. 

This is the most complete Book of Formulas ever published, giving thousands of recipes for 
the manufacture of valuable articles for everyday use. Hints, Helps, Practical Ideas, and 
Secret Processes are revealed within its pages. It covers every branch of the useful arts and 
tells thousands of ways of making money, and is just the book everyone should have at his 
command. 

Modern in its treatment of every subject that properly falls within its scope, the book may 
truthfully be said to present the very latest formulas to be found in the arts and industries, 
and to retain those processes which long experience has proven worthy of a permanent record. 
To present here even a limited number of the subjects which find a place in this valuable work 
would be difficult. Suffice to say that in its pages will be found matter of intense interest and 
immeasurably practical value to the scientific amateur and to him who wishes to obtain a 
knowledge of the many processes used in the arts, trades and manufacture, a knowledge 
which will render his pursuits more instructive and remunerative. Serving as a 

reference book to the small and large manufacturer and supplying intelligent seekers with the 
information necessary to conduct a process, the work will be found of inestimable worth to 
the Metallurgist, the Photographer, the Perfumer, the Painter, the Manufacturer of Glues, 
Pastes, Cements, and Mucilages, the Compounder of Alloys, the Cook, the Physician, the 
Druggist, the Electrician, the Brewer, the Engineer, the Foundryman, the Machinist, the 
Potter, the Tanner, the Confectioner, the Chiropodist, the Manicurist, the Manufacturer of 
Chemical Novelties and Toilet Preparations, the Dyer, the Electror>later, the Enameler, the 
Engraver, the Provisioner, the Glass Worker, the Goldbeater, the Watchmaker, the Jeweler, 
the Hat Maker, the Ink Manufacturer, the Optician, the Farmer, the Dairyman, the Paper 
Maker, the Wood and Metal Worker, the Chandler and Soap Maker, the Veterinary Surgeon, 
and the Technologist in general. 

A mine of information, and up-to-date in every respect. A book which will prove of value 
to EVERYONE, as it covers every branch of the Useful Arts. Every home needs this book; 
every office, every factory, every store, every public and private enterprise — EVERYWHERE 
— should have a copy. 800 pages. Price $3.00 

WHAT IS SAID OF THIS BOOK: 

"Your Twentieth Century Book of Recipes, Formulas, and Processes duly received. I am 
glad to have a copy of it, and if I could not replace it, money couldn't buy it. It is the best 
thing of the sort I ever saw." (Signed) M. E. Trux, Sparta, Wis. 

" There are few persons who would not be able to find in the book some single formula that 
would repay several times the cost of the book." — Merchants' Record and Show Window. 

"I ourchased your book, 'Henley's Twentieth Century Book of Recipes, Formulas and Proc- 
esses,' about a year ago and it is worth its weight in yold." — Wm. II. Murray, Bennington, Vt. 

"ONE OF THE WORLD'S MOST USEFUL BOOKS" 

"Some time ago I got one of your 'Twentieth Century Books of Formulas,' and have made 
my living from it ever since. I am alone since my husband's death with two small children 
to care for and am trying so hard to support them. I have customers who take from me 
Toilet Articles I put up, following directions given in the hook, and I have found everyone of 
them to be fine." — Mrs. J. H. McMakkn, West Toledo, Ohio. 



30 THE NORMAN W. HENLEY PUBLISHING CO. 

RUBBER 

Rubber Hand Stamps and the Manipulation of India Rubber. By T. 

O'Conor Sloane. 

This book gives full details on all points, treating in a concise and simple manner the elements 
of nearly everything it is necessary to understand for a commencement in any branch of the 
India Rubber Manufacture. The making of all kinds of Rubber Hand Stamps, Small Articles 
of India Rubber, U. S. Government Composition, Dating Hand Stamps, the Manipulation of 
Sheet Rubber, Toy Balloons, India Rubber Solutions, Cements, Blackings, Renovating, 
Varnish, and Treatment for India Rubber Shoes, etc.; the Hektograph Stamp Inks, and Mis- 
cellaneous Notes, with a Short Account of the Discovery, Collection and Manufacture of India 
Rubber, are set forth in a manner designed to be readily understood, the explanations being 
plain and simple. Including a chapter on Rubber Tire Making and Vulcanizing; also a 
chapter on the uses of rubber in Surgery and Dentistry. 3rd Revised and Enlarged Edition. 
175 pages. Illustrated $1.00 

SAWS 

Saw Filing and Management of Saws. By Robert Grimshaw. 

A practical hand-book on riling, gumming, swaging, hammering, and the brazing of band 
saws, the speed, work, and power to run circular saws, etc. A handy book for those who have 
charge of saws, or for those mechanics who do their own filing, as it deals with the proper 
shape and pitches of saw teeth of all kinds and gives many useful hints and rules for gumming, 
setting, and filing, and is a practical aid to those who use saws for any purpose. Complete 
tables of proper shape, pitch, and saw teeth as well as sizes and number of teeth of various 
saws are included. 3rd Edition, Revised and Enlarged. Illustrated. Price $1.00 



STEAM ENGINEERING 

American Stationary Engineering. By W. E. Crane. 

This book begins at the boiler room and takes in the whole power plant. A plain talk on 
every-day work about engines, boilers, and their accessories. It is not intended to be scien- 
tific or mathematical. All formulas are in simple form so that any one understanding plain 
arithmetic can readily understand any of them. The author has made this the most practical 
book in print; has given the results of his years of experience, and has included about all that 
has to do with an engine room or a power plant. You are not left to guess at a single point. 
You are shown clearly what to expect under the various conditions; how to secure the best 
results; ways of preventing "shut downs" and repairs; in short, all that goes to make up the 
requirements of a good engineer, capable of taking charge of a plant. It's plain enough for 
practical men and yet of value to those high in the profession. 

A partial list of contents is: The boiler room, cleaning boilers, firing, feeding; pumps, inspec- 
tion and repair; chimneys, sizes and cost ; piping; mason work; foundations; testing cement; 
pile driving; engines, slow and high speed; valves; valve setting; Corliss engines, setting 
valves, single and double eccentric; air pumps and condensers; different types of conden- 
sers; water needed; lining up; pounds; pins not square in crosshead or crank; engineers' 
tools; pistons and piston rings; bearing metal; hardened copper; drip pipes from cylinder 
jacket; belts, how made, care of; oils; greases; testing lubricants; rules and tables, in- 
cluding steam tables; areas of segments; squares and square roots; cubes and cube root; 
areas and circumferences of circles. Notes on: Brick work; explosions; pumps; pump 
valves; heaters, economizers; safety valves; lap, lead, and clearance. Has a complete ex- 
amination for a license, etc., etc. 3rd Edition. 345 pages, illustrated. Price . . . .$2.00 

Engine Runner's Catechism. By Robert Grimshaw. 

A practical treatise for the stationary engineer, telling how to erect, adjust, and run the 
principal steam engines in use in the United States. Describing the principal features of vari- 
ous special and well-known makes of engines: Temper Cut-off, Snipping and Receiving Founda- 
tions, Erecting and Starting, Valve Setting, Care and Use, Emergencies, Erecting and Ad- 
justing Special Engines. 

The questions asked throughout the catechism are plain and to the point, and the answers 
are given in such simple language as to be readily understood by anyone. All the instructions 
given are complete and up-to-date; and they are written in a popular style, without any 
technicalities or mathematical formula?. The work is of a handy size for the pocket, clearly 
and well printed, nicely bound, and profusely illustrated. 

To young engineers this catechism will be of great value, especially to those who may be 
preparing to go forward to be examined for certificates of competency; and to engineers 
generally it will be of no little service, as they will find in this volume more really practical 
and useful information than is to be found anywhere else within a like compass. 387 pages. 
7th Edition. Price $2.00 



CATALO GUE OF GOOD, PRACTICAL BOOKS 31 

Modern Steam Engineering in Theory and Practice. By Gardner D. 
Hiscox. 

This is a complete and practical work issued for Stationary Engineers and Firemen, dealing 
with the care and management of boilers, engines, pumps, superheated steam, refrigerating 
machinery, dynamos, motors, elevators, air compressors, and all other branches with which 
the modern engineer must be familiar. Nearly 200 questions with their answers on steam 
and electrical engineering, likely to be asked by the Examining Board, are included. 
Among the chapters are: Historical: steam and its properties; appliances for the generation 
of steam; types of boilers; chimney and its work; heat economy of the feed water; steam 
pumps and their work; incrustation and its work; steam above atmospheric pressure; flow 
of steam from nozzles; superheated steam and its work; adiabatic expansion of steam; indi- 
cator and its work; steam engine proportions; slide valve engines and valve motion; Corliss 
engine and its valve gear; compound engine and its theory; triple and multiple expansion 
engine; steam turbine; refrigeration; elevators and their management; cost of power; steam 
engine troubles; electric power and electric plants. 487 pages, 405 engravings. 3rd Edition. 
Price §3.00 

Steam Engine Catechism. By Robert Gremshaw. 

This unique volume of 413 pages is not only a catechism on the question and answer principle 
but it contains formulas and worked-out answers for all the Steam problems that appertain to 
operation and management of the Steam Engine. Illustrations of various valves and valve 
gear with their principles of operation are given. Thirty-four Tables that are indispensable 
to every engineer and fireman that wishes to be progressive and is ambitious to become master 
of his calling are within its pages. It is a most valuable instructor in the service of Steam 
Engineering. Leading engineers have recommended it as a valuable educator for the begin- 
ner as well as a reference book for the engineer. It is thoroughly indexed for every detail. 
Every essential question on the Steam Engine with its answer is contained in this valuable 
work. 16th Edition. Price . $2,00 

Steam Engineer's Arithmetic. By Colvin-Cheney. 

A practical pocket-book for the steam engineer. Shows how to work the problems of the 
engine room and shows "why." Tells how to figure horsepower of engines and boilers; area 
of boilers; has tables of areas and circumferences; steam tables; has a dictionary of engineering 
terms. Puts you on to all of the little kinks in figuring whatever there is to figure around a 
power plant. Tells you about the heat unit; absolute zero; adiabatic expansion; duty of 
engines; factor of safety; and a thousand and one other things; and everything is plain and 
simple — not the hardest way to figure, but the easiest. 2nd Edition. Price . . 5Q Cents 

Engine Tests and Boiler Efficiencies. By J. Buchetti. 

This work fully describes and illustrates the method of testing the power of steam engines, 
turbines and explosive motors. The properties of steam and the evaporative power of fuels. 
Combustion of fuel and chimney draft; with formulas explained or practically commuted. 
255 pages, 179 illustrations. Price 83.00 

Horsepower Chart. 

Shows the horsepower of any stationary engine without calculation. No matter what the 
cylinder diameter of stroke, the steam pressure of cut-off, the revolutions, or whether con- 
densing or non-condensing, it's all there. Easy to use, accurate, and saves time and calcula- 
tions. Especially useful to engineers and designers. Price 50 Cents 

STEAM HEATING AND VENTILATION 

Practical Steam, Hot-Water Heating and Ventilation. By A. G. King. 

This book is the standard and latest work published on the subject and has been prepared for 
the use of all engaged in the business of steam, hot-water heating, and ventilation. It is an 
original and exhaustive work. Tells how to get heating contracts, how to install heating and 
ventilating apparatus, the best business methods to be used, with "Tricks of the Trade" for 
shop use. Rules and data for estimating radiation and cost and such tables and information 
as make it an indispensable work for everyone interested in steam, hot-water heating, and 
ventilation. It describes all the principal systems of steam, hot-water, vacuum, vapor, and 
vacuum-vapor heating, together with the new accelerated systems of hot-water circulation, 
including chapters on up-to-date methods of ventilation and the fan or blower system of heat- 
ing and ventilation. Containing chapters on: I. Introduction. II. Heat. III. Evolution 
Of artificial heating apparatus. IV. Boiler surface and settings. V. The chimney flue. 
VI. Pipe and fittings. VII. Valves, various kinds. VIII. Forms of radiating surfaces. IX. 



32 



THE NORMAN W. HENLEY PUBLISHING CO. 



Locating of radiating surfaces. X. Estimating radiation. XI. Steam-heating apparatus. 
XII. Exhaust-steam heating. XIII. Hot-water heating. XIV. Pressure systems of hot-water 
work. XV. Hot-water appliances. XVI. Greenhouse heating. XVII. Vacuum vapor and 
vacuum exhaust heating. XVIII. Miscellaneous heating. XIX. Radiator and pipe connec- 
tions. XX. Ventilation. XXI. Mechanical ventilation and hot-blast heating. XXII. 
Steam appliances. XXIII. District heating. XXIV. Pipe and boiler covering. XXV. Tem- 
perature regulation and heat control. XXVI. Business methods. XXVII. Miscellaneous. 
XXVIII. Rules, tables, and useful information. 367 pages, 300 detailed engravings. 2nd 
Edition — Revised. Price $3.00 

Five Hundred Plain Answers to Direct Questions on Steam, Hot-Water, 
Vapor and Vacuum Heating Practice. By Alfred G. King. 

This work, just off the press, is arranged in question and answer form; it is intended as a 
guide and text-book for the younger, inexperienced fitter and as a reference book for all 
fitters. This book tells "how" and also tells "why". No work of its kind has ever been 
published. It answers all the questions regarding each method or system that would be 
asked by the steam fitter or heating contractor, and may be used as a text or reference book, 
and for examination questions by Trade Schools or Steam Fitters' Associations. Rules, data, 
tables and descriptive methods are given, together with much other detailed information of 
daily practical use to those engaged in or interested in the various methods of heating. Val- 
uable to those preparing for examinations. Answers every question asked relating to modern 
Steam, Hot-Water, Vapor and Vacuum Heating. Among the contents are: The Theory and 
Laws of Heat. Methods of Heating. Chimneys and Flues. Boilers for Heating. Boiler 
Trimmings and Settings. Radiation. Steam Heating. Boiler, Radiator and Pipe Connec- 
tions for Steam Heating. Hot Water Heating. The Two-Pipe Gravity System of Hot Water 
Heating. The Circuit System of Hot Water Heating. The Overhead System of Hot Water 
Heating. Boiler, Radiator and Pipe Connections for Gravity Systems of Hot Water Heat- 
ing. Accelerated Hot Water Heating. Expansion Tank Connections. Domestic Hot Water 
Heating- Valves and Air Valves. Vacuum Vapor and Vacuo-Vapor Heating. Mechanical 
Systems of Vacuum Heating. Non-Mechanical Vacuum Systems. Vapor Systems. Atmos- 
pheric and Modulating Systems. Heating Greenhouses. Information, Rules and Tables. 
200 pages, 127 illustrations. Octavo. Cloth. Price , $1.50 



STEEL 



Steel: Its Selection, Annealing, Hardening, and Tempering. 

Markham. 



By E. R. 



This work was formerly known as "The American Steel Worker," but on the publication 
of the new, revised edition, the publishers deemed it advisable to change its title to a more 
suitable one. It is the standard work on Hardening, Tempering, and Annealing Steel of all kinds. 
This book tells how to select, and how to work, temper, harden, and anneal steel for every- 
thing on earth. It doesn't tell how to temper one class of tools and then leave the treatment 
of another kind of tool to your imagination and judgment, but it gives careful instructions 
for every detail of every tool, whether it be a tap, a reamer or just a screw-driver. It tells 
about the tempering of small watch springs, the hardening of cutlery, and the annealing of 
dies. In fact, there isn't a thing that a steel worker would want to know that isn't included. 
It is the standard book on selecting, hardening and tempering all grades of steel. Among 
the chapter headings might be mentioned the following subjects: Introduction; the work- 
man; steel; methods of heating; heating tool steel; forging; annealing; hardening baths; 
baths for hardening; hardening steel; drawing the temper after hardening; examples of 
hardening; pack hardening; case hardening; spring tempering; making tools of machine 
steel; special steels; steel for various tools; causes of trouble; high-speed steels, etc. 400 
pages. Very fully illustrated. Fourth edition. Price $£ .50 



Hardening, Tempering, Annealing, and Forging of Steel. 

WORTH. 



By J. V. Wood- 



A new work treating in a clear, concise manner all modern processes for the heating, anneal- 
ing, forging, welding, hardening and tempering of steel, making it a book of great practical 
value to the metal-working mechanic in general, with special directions for the successful 
hardening and tempering of all steel tools used in the arts, including milling cutters, taps, thread 
dies, reamers, both solid and shell, hollow mills, punches and dies, and all kinds of sheet- 
metal working tools, shear blades, saws, fine cutlery, and metal-cutting tools of all descrip- 
tion, as well as for all implements of steel both large and small. In this work the simplest 
and most satisfactory hardening and tempering processes are given. 

The uses to which the leading brands of steel may be adapted are concisely presented, and 
their treatment for working under different conditions explained, also the special methods 
for the hardening and tempering of special brands. 

A chapter devoted to the different processes for case-hardening is also included, and special 
reference made to the adaptation of machinery steel for tools of various kinds. Fourth edi- 
tion. 288 pages. 201 illustrations. Price $3.50 



CATALOGUE OF GOOD, PRACTICAL BOOKS 33 

TRACTORS 

The Modern Gas Tractor. By Victor W. Page, M.E. 

A complete treatise describing all types and sizes of gasoline, kerosene and oil tractors. Con- 
siders design and construction exhaustively, gives complete instructions for care, operation 
and repair, outlines all practical applications on the road and in the field. The best and 
latest work on farm tractors and tractor power plants. A work needed by farmers, students, 
blacksmiths, mechanics, salesmen, implement dealers, designers, and engineers. Second edition, 
revised and enlarged. 504 pages. Nearly 300 illustrations and folding plates. Price §2 .00 



TURBINES 

Marine Steam Turbines. By Dr. G. Bauer and O. Lasche. Assisted by 
E. Ludwig and H. Vogel. 

Translated from the German and edited by M. G. S. Swallow. The book is essentially prac 
tical and discusses turbines in which the full expansion of steam passes through a number 
of separate turbines arranged for driving two or more shafts, as in the Parsons system, and 
turbines in which the complete expansion of steam from inlet to exhaust pressure occurs in 
a turbine on one shaft, as in the case of the Curtis machines. It will enable a designer to 
carry out all the ordinary calculation necessary for the construction of steam turbines, hence 
it fills a want which is hardly met by larger and more theoretical works. Numerous tables, 
curves and diagrams will be found, which explain with remarkable lucidity the reason why 
turbine blades are designed as they are, the course which steam takes through turbines of 
various types, the thermodynamics of steam turbine calculation, the influence of vacuum 
on steam consumption of steam turbines, etc. In a word, the very information which a de- 
signer and builder of steam turbines most requires. Large octavo, 214 pages. Fully illustrated 
and containing eighteen tables, including an entropy chart. Price, net §3 .50 



WATCH MAKING 

Watchmaker's Handbook. By Claudius Sauxier. 

No work issued can compare with this book, for clearness and completeness. It contains 
498 pages and is intended as a workshop companion for those engaged in watch-making and 
allied mechanical arts. Nearly 250 engravings and fourteen plates are included. This is 
the standard work on watch-making. Price S3 „Q0 



WELDING 

Automobile Welding with the Oxy-Acetylene Flame. By M. Keith Dunham. 

Explains in a simple manner apparatus to be used, its care, and how to construct necessary 
shop equipment. Proceeds then to the actual welding of all automobile parts, in a manner 
understandable by every one. Gives principles never to be forgotten. Aluminum, cast iron, 
Btee!, copper, brass, bronze, and malleable iron are fully treated, as well as a clear explana- 
tion of the proper manner to burn the carbon out of the combustion head. This book is of 
utmost value, since the perplexing problems arising when metal is heated to a melting point 
are fully explained and the proper methods to overcome them shown. 167 pages, fully illus- 
trated. Price 81.00 



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